Gen 2: Secondary Air Injection System Bypass Kit (Plug & Play)

(77 customer reviews)


The Gen 2 Bypass Kit is the most comprehensive unit and our recommended solution. It enables you to clear the Check Engine Light, Limp Mode and error codes related to both mechanical and electrical SAIS faults. Bypass kit will also include Block off Plate(s). Compatible with Standard Fuel & Flex Fuel vehicles.

If your vehicle is not listed, please use “Search By Vehicle” feature to find compatible products.
SKU: G2- Plug & Play Categories: , , Tags: , ,



Hewitt Tech Generation 2 Secondary Air Injection System Bypass Kit (Plug & Play)

The Hewitt Tech (HT) Gen 2 (Plug & Play) Bypass Kit comes in 1 Bank and 2 Bank variations. The Gen 2 is our most comprehensive bypass kit and for this reason is our recommended solution. It emulates the operation of the SAIS by replacing the Air Injection Drivers (AID). It enables you to clear the Check Engine Light, Limp Mode and error codes related to mechanical and electrical SAIS faults. Additionally, the SAIS system monitor will even show as complete/ready. The Gen 2 (Plug & Play) is compatible with most Toyota and Lexus vehicles model years ’07 – Current. This includes Flex Fuel Models and vehicles that have had the ECM flashed with new calibration file. This version of the Gen 2 Bypass kit offers a complete Plug & Play kit with connectors compatible with the vehicle’s factory components. It includes Block Off Plate(s) but will NOT need installation of the Starter Relay Wire. It is made with automotive grade materials and designed to blend in with the factory wiring harness. This allows for a very clean factory looking installation. Easy to follow step by step installation instructions are included with vehicle specific illustrations. The Gen 2 (Plug & Play) Bypass kit is simply the best solution for both professionals and DIY mechanics because of the ease of install and comprehensive coverage. It is also the ideal solution for anyone looking to remove the Air Pumps or Air Switching Valves to create more room in the engine bay for aftermarket modifications.

It is Important to understand that HT SAIS Bypass kits are engineered to work with Factory or OEM SAIS components. That said, aftermarket SAIS components can cause fault codes to be present after installation of the bypass kit. This typically means you will need HT Kit Addon(s) in order to clear SAIS codes that are still present.

The following are Secondary Air Injection System Trouble codes the Gen 2 Bypass Kit typically addresses*:

Mechanical Codes

P1441 – Switching Valve No.2 Stuck Open Bank 1
P1442 – Switching Valve No.2 Stuck Close Bank 1
P1444 – Switching Valve No.2 Stuck Open Bank 2
P1445 – Switching Valve No.2 Stuck Close Bank 2
P2440 – Switching Valve Stuck Open Bank 1
P2441 – Switching Valve Stuck Closed Bank 1
P2442 – Switching Valve Stuck Open Bank 2
P2443 – Switching Valve Stuck Closed Bank 2
P2445 – Pump Stuck OFF Bank 1**
P2447 – Pump Stuck Off Bank 2

Electrical Codes

P0412 – SAIS Switching Valve ‘A’ Circuit Malfunction Bank 1
P0415 – SAIS Switching Valve ‘B’ Circuit Malfunction Bank 2
P0418 – SAIS Circuit/Relay ‘A’ Circuit Malfunction Bank 1
P0419 – SAIS Circuit/Relay ‘B’ Circuit Malfunction Bank 2

The following are Trouble codes NOT addressed by the Gen 2 Bypass. These will require kit addon(s) in order to clear.

Pressure Sensor Codes

P2431 – Air Flow / Pressure Sensor Circuit Range / Performance Bank1
P2432 – Air Flow / Pressure Sensor Circuit Low Bank 1
P2433 – Air Flow / Pressure Sensor Circuit High Bank 1
P2436 – Air Flow / Pressure Sensor Circuit Range / Performance Bank 2
P2437 – Air Flow / Pressure Sensor Circuit Low Bank 2
P2438 – Air Flow / Pressure Sensor Circuit High Bank 2
P106B – Pressure Sensor Correlation / Evap. Pressure Sensor

These codes typically indicate a damaged Pressure Sensor which is usually caused by an Air Switching Valve being stuck open for an extended period of time. Functioning Pressure Sensors are needed for both Gen 1 and Gen 2 Bypass kits. Compatible Pressure Sensor addon required in order to clear.


  • 1 x SAIS Bypass Module – Plug & Play Connections (AIDs)
  • 1 x SAIS Bypass Harness – Plug & Play Connections (ASVs)
  • 2 x Secondary Exhaust Valve Block Off Plates (Engine Specific)
  • Stainless Steel Mounting Hardware
    • 2 x Stainless Steel Screws
    • 2 x Stainless Steel 10 mm Hex Nuts
  • Installation Accessories
    • 2 x Plugs for Factory AID Wiring Harness
    • 4 x ‘3 Inch Zip Ties
  • 1 x Printed Copy – Detailed Bypass Module Installation Instructions
  • 1 x Printed Copy – Block Off Plate Instructions (Engine Specific)


  • Bypass Module:
    • Custom Molded Black Duroplastic High Temp Enclosure – UL 94 V-0 Flame Resistance
    • Black Epoxy Potted for environmental and shock protection.
  • Bypass Wiring Harness:
    • Straight forward Plug & Play connections compatible with Factory components.
    • High Quality Automotive Engine Compartment Grade TXL Wiring
  • Block Off Plates:
    • 16 gauge (1/16 inch) 316 Stainless Steel Block Off Plate Construction for Lifetime Use
    • Water Jet Cut for Precision and Smoother Edges, Guaranteed to Fit Your Engine
  • Assembled 100% by hand in the USA!
  • Limited Life-Time Warranty


The Gen 2 Bypass kit is the best solution to address or prevent Secondary Air Injection issues. Unlike the Gen 1 Bypass kits which only manipulates the operation of the SAIS, the Gen 2 Bypass kit fully emulates it. Why is this an advantage? First, the Gen 2 can cover both Mechanical and Electrical SAIS fault codes. This limits the potential need of kit addons in the future. Second, the Gen 2 is compatible with Toyota’s most recent ECM flashes and recalibrations. This includes ECM programming for Flex Fuel models. Lastly, since the Gen 2 is emulating the SAIS system this means monitors will show as ready and complete even if the entire system is removed from the vehicle. The Gen 2 allows you remove the Air Pump(s), plumbing, Air Injection control drivers – and by adding Pressure Sensors Options (PSO), you can also remove the air switching valves. For those looking for a complete SAIS delete kit, this is the way to go.

When designing the Gen 2, it was critical the bypass seamlessly integrate with factory components and blend in under the hood. As a result, all connections for Gen 2 kit were engineered to be Plug & Play. This is another major advantage over the Gen 1 units because you do not have to worry about splicing into the factory harness or running a Starter Relay Wire to the fuse box. Additionally, HT had the protective enclosure costume molded to imitate the factory Air Injection Drivers. This allows you to mount directly to existing brackets. This in combination with the Plug & Play harness makes for a very professional and factory looking installation.

The included Air Switching Valve Block-off Plates are an integral part of the bypass kit. The Block Off Plates are the only way to isolate the Air Switching Valves and protect the related Pressure Sensor(s) from damage caused by exhaust. Open Air Switching Valves and Pressure Sensors exposed to exhaust are the primary cause of Limp Mode and SAIS failure.

It is important to understand that installing a HT bypass will prevent your Air Pumps and Air Switching Valves from operating. However, it will not close the Air Switching Valves or keep them closed in the future. That said, choosing not to install the Block Off Plates leaves the SAIS vulnerable because exhaust may leak into open valves and damage the Pressure Sensors. As noted above, both Gen 1 & 2 HT bypass kits require kit addons to clear SIAS Pressure Sensor codes. Do yourself a favor, avoid future frustrations and costs; install the Block Off Plates.

If you are having a hard time determining which is the best solution for your vehicle, please do not hesitate to give us a call or send an email. Hewitt is here to help!


*The vehicles fuses, Pressure Senor(s), factory wiring harness and Engine Control Module (ECM) must be in good working condition for bypass kit to operate properly.

**There is a known “Cold Weather Glitch” on some older 4.7L engines. If the vehicle is tripping a P2445 and it is caused by this glitch; the Hewitt Technologies SAIS Bypass Kit will not resolve the issues. Please visit our Error Codes page or give us a call to learn more.


It is illegal to remove, dismantle or otherwise cause to be inoperative any pollution control device required by federal, state, or local emissions law. Our bypass kits are sold for off-road, competition or other emissions exempt vehicles only. No other applications are intended or implied. By installing or using this SAIS Bypass Kit the vehicle owner and installer acknowledge and assumes ALL risks associated with its use.

Additional information

Weight 1 lbs
Dimensions 8 × 7 × 2 in

2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021


Lexus, Toyota


Tundra, Sequoia, 4Runner, Tacoma, Land Cruiser, FJ Cruiser, Hilux, GX 460, LX 570


2.7L, 4.0L, 4.6L, 4.7L, 5.7L, 5.7LFlexFuel

77 reviews for Gen 2: Secondary Air Injection System Bypass Kit (Plug & Play)

  1. colinperkins49

    Colin Perkins, Canada
    I purchased the Gen II bypass kit in May 2022 + the PSOs for a 4.7l 2007 Tundra. It worked great for about one year then threw a few error codes, but did not go into limb mode. Contacted HT & they are great to deal with. They suggested a few things to try which eliminated the errors for awhile. I would send an email once in awhile to let them know what was happening. Although the error codes showed up the motor did not go into limp mode. In May 2024 HT decided to send a new module at their cost to repair the problem. I installed the new module & have had no issues so far.

    This is the first review I have ever written about a product, but their service & warranty are so good that it is definitely worth sending a review to alleviate anyones concern of dealing with HT or buying their product. I was leery at first as I have been scammed by other products which turned out to be duds with no money back or help in correcting the problem. HT is a very reputable company to deal with!

  2. Paul Pearman (verified owner)

    Just fitted this to my 2007 4.7L Tundra (191,000miles). It was super easy to fit. I made one mistake, the water hose near valve 2 was in the way so I decided to move it . Just needed to top up the radiator afterwards and I was back in business. I had tried to fit a new Bank 1 valve as that was the only warning code but after I did I got even more warning lights , including traction control, oil temp etc. So I took out the “new” valve put the old stuck one back and fitted the bypass kit. All error codes gone and the truck is running beautifullky again. Thanks for a really easy to fit kit. I only hope it passes the smog check next year, I’m sure the system will work , but some eagle eyed examiner may see the kit has been fitted..

  3. jonathankirk000 (verified owner)

    Got this gen II plug n play kit for my 2007 4.7 tundra and it fixed my problems completely! I don’t think my truck has ever ran this well! Installed the wire harness and the block off plates in the secondary injection valves bank 1 and two. And with this kit was able to remove the pump completely. Highly recommend this product great job Hewitt tech! Also can’t forget to mention the exceptional customer service! I called multiple time with questions that were all answered could not be more satisfied with my purchase!

  4. bmpeters2001 (verified owner)

    I installed the Gen-II on my 2011 Tundra 4.6L with relative ease and it only took two hours. Hewitt’s YouTube videos helped immensely, plus a couple of others I found demonstrating the installation process.
    The CEL came back on shortly after installation of the bypass kit. I emailed Hewitt support and the owner replied immediately. That in itself spoke volumes to me about this company! Mr. Hewitt suggested I install the optional pressure sensor on Bank 1 to see if it would resolve the codes I was getting. I was impressed that he did not try to convince me into buying a pressure sensor for Bank 2 unless I truly needed it. Turns out I did indeed need the second pressure sensor which took all of one minute to install. Since then, my truck has been running like a champ!
    Finally, each time I placed an order I paid for overnight shipping from their location in SC to Dallas, TX and the part was sitting on my doorstep by 9:00 AM the next day. Again, great customer service. I highly recommend this company and their products!

  5. Scott Gray (verified owner)

    Fantastically satisfied with the Hewitt Bypass. Wow is another word I can use to describe. This saved me over $2,000 and I could not be happier. Shipping to Alaska was faster than most thing I get shipped from Amazon. Thanks, Hewitt Tech, for designing this low-cost fix for something Toyota should have done.

  6. joshhudgins123

    I had been dealing with limp mode issues for over two weeks, I had enough. I had been looking at this kit for a while and was waiting due to the price to save up. but after having no engine power for so long I took the plunge. let me tell you it was worth every cent, it immediately got rid of the limp mode , it felt like a god sent I’m sure others would agree on. the electronics were easy to install and the instructions were very detailed, including additional notes for my specific model which I appreciated. only issue I ran into was with the block off plates. I was able to install one on the front side but the side going into the firewall had odd placement and the nuts were rounded off. after a quick call to confirm an alternant location to install I was set and it worked. id absolutely recommend this to anyone, the quality, customer service, and attention to detail is second to none.

    My only con I have is a suggestion to HT, add a smaller diameter block off plate for the passenger side manifold flange. the two that it came with were made to fit on the air switching valve assembly but were slightly too large for the flange I had to use. (for reference see figure 1 of 08 toy tundra 4.0L plate mounting instructions) it would be nice to include one plate incase someone runs into the issue I ran into after I installed everything else. otherwise you have to modify the plate slightly to allow it to fit, now if there is one that will fit properly I may purchase it later on if not that would be a great addition to add for sale or to be included.

    overall 10/10.

  7. bennett4433

    Worked as advertised. Purchased this and 2 pressure sensor replacements. Been a couple months and there are no codes. Install was extremely easy and was done with a flat head, some encouragement from my fist and a 1/4 ratchet.

  8. derbysnooksniper (verified owner)

    Kinda worked, still needed snap-on level scanner to re-map my pcm. Slightly mislead still had , p2441, p2443, p2447 and another I can’t remember right not, came back 3 days later.

    • Paul Hewitt (verified owner)

      I am sorry to see you left less than a 5-star review. Other than clearing the codes during or after installation, there should be no need. Please give us a call or email us directly if you need further help resolving any problems after your current installation. Unfortunately, the kits sometimes take a little more Hopefully, everything is working like it should now but if anything changes just let us know and we are here to help if we can. We see a lot of problems with damaged or aftermarket sensors as well as damaged wiring or connectors that unfortunately take a little more troubleshooting and even an add-on to resolve correctly. Hopefully, everything is working like it should after installing your pressure sensor add-on but if anything changes just let us know and we are here to help if we can.

  9. brtbull44

    In response to a P2443 code, I installed Hewitt’s Gen 2 Bypass Kit in my 2007 Tundra 5.7 a couple of weeks ago and fixed the problem. Spray the bolts in the wheel well several times during the evening where you install the block plates and let them sit overnight, and loosened mine in the morning, no problem. And I’m in the rust belt and my truck is 16 years old. I used a shorter length of broomstick handle and rubber mallet on studs to loosen exhaust flanges, and prybar, to push studs up just enough to slide plates in. Regarding the two final electrical connections at the rear of the motor, Practice undoing on the new ones that comes with the kit, or practice on the one mounted on your air cleaner housing. Put a trouble light back there because if you can get a visual on it, it really helps. The drivers side is easier to access and depress, it’s sitting right at the corner. If you have trouble depressing the clip, my thumb’s kind of fat and wide so I taped a one inch long piece of very small dowelling up the centre of my thumb, a little piece of a twig off a tree would work fine. The passenger side, I threw a cushion down and climbed up there and I could barely see the clip past the wiring harness, but good enough to get a dental pick on it with my right hand, lift the locking clip just high enough to clear, and with my left hand in place and my fingertips just able to grab the connector, pull it apart…and Bob’s your Uncle! Then hooking up the kit connectors is easy and away you go! Tech support is outstanding if you need help!

  10. johnny7175

    Derek & the Hewitt team are point on with their Customer service instructions.E-mailed me installation instructions and also included Pictured instructions within the GEN II kit package that included the Bank 2 sensor add on that I needed to clear out the P-2437 code that caused the limp mode function and ck. Engine /track off lights on my 2012 4.6l engine. (1st occurrence 2018,@ $1100. was pump replacement 70K miles). # 2 was in 2020 at $700. Cost for bank 1 valve replacement at 100K miles. Where does the bleeding stop? #3 is at 123K miles.Kit included electrical blanking caps plus very detailed instructions right down to disconnecting the fluid level sensor plug on the master cylinder for convience plus disconnecting the negative cable from the Battery. The increased MPG from the 15.5 adverage to a now 18.3 is an unexpected BONUS. Upon engine re-start engine will run a bit rough as the onboard tuning is automatic & will restore the smile on your face.
    Performance and pep is better than it ever was on my 2012 Tundra. Maybe a keeper NOW. Saved me $$$$.

  11. serge

    Absolutely happy with the kit along with the customer service. Fast free shipping, nice packaging and high quality product. Super detailed and easy to follow instructions. Highly recommended! Spend money and time once.

  12. rgruetzman

    Just wanted to thank you for the great support and speed of delivery. I called of the Friday and had the module on Monday. Plugged it in and my Tundra is back running properly.

    I couldn’t ask for a better experience.

  13. rcholmes996 (verified owner)

    This kit worked like a charm on my 2011 tundra with 5.7l v8. Quality was superb and instructions were spot on with great pictures. Bank was very difficult to get at connector but that was explained in instructions and you tube video so I was expecting it. Truck is running like a champ now. Thanks again Hewitt tech!

  14. Jordan Chamberlain

    I can’t say enough great things about Hewitt-Tech and their product. I’ll start off with my ordering experience. Once I placed my order they shipped out the product asap via USPS. Long story long I received a notification from USPS that my package had been delivered to my doorstep. I checked my front door, no package. I double checked my ring, no notifications. After trying for days to reach someone by phone at my local post office I had zero luck. I went down in person and they said they would look into it and call me back. I wait a week with no phone call and go back in. They tell me the package was not found. I reached out to Hewitt-Tech and explained the story. The package was insured so they submitted a claim and immediately overnighted me another package via FedEx. Their customer service is top notch.

    The next day I receive the package and installation was a breeze. They send very detailed instructions. I was lucky and had a relatively smooth install as it only took me about an hour. Once I got it all buttoned up I took it for a drive – it’s better than new. It even feels like it runs stronger than before so the placebo effect comes with the product at no additional charge. My only regret is that I didn’t buy this sooner. I had been driving with the check engine light and these codes for months now. Thank you to everyone at Hewitt-Tech.

  15. chris_heard

    Just installed Gen II on my 2011 Tundra with 4.6L Engine. Took 2.5hrs. Rusted bolts under brackets holding AIDs slowed me way down. I sheared the heads off of 2 of them, can’t believe those bolts extend into the wheel well exposed to salt. My bracket is held on with 1 bolt and a few attachments to wiring harness clips. Will need to get them drilled out in the future. Backoff plates required loosening all three 12mm bolts holding the ASVs on the engine block. Once the ASV is loose, you can open up a gap just big enough for the block off plates to install. First start of the engine was a success. I have run the truck over the last week and …oh my god…best thing I have ever done to any vehicle.

  16. twarren189

    Great product. I highly recommend installing the Gen2 system instead of the Gen1 system. Just spend the money and buy it. I installed the Gen2 with a pressure sensor on my 2007 Tundra 4×4 and it works great. The exhaust bypass plates are a major pain in the butt, I rushed and now have an exhaust leak on the passenger side, which is the hardest side to install. So, take your time when doing these! The wiring is plug and play and very simple. I have had it installed for over 10,000 miles and no problems. This is a great company and everyone I spoke to on the phone knows what they are talking about.

  17. jonathanjensonllc

    If I could give this product 10 stars I would.
    Bought the Gen 2 with extra sensor. Well worth every dollar.
    On my 07 tundra with the 4.7 I was constantly in limp mode, cutting off. I was so frustrated I was going to just trade it off. But I found this set up and wow and I mean WOW!!!!! it made me love my truck again.
    My gas mpg went from 9.2 to 15.8 in the 1st tank.
    Guys or gals….. its well worth the money to do this upgrade. The gas mileage savings alone will pay for it in no time and the power of the truck improves so much you will think you put a new engine in. The other thing that surprises me is it quieted the engine so much and my tach is so stable. Purchase this you won’t be sorry and installing it is so simple it’s crazy.

    Again guy who invented this for us Toyota lovers, great freaking job!

  18. Mark Hill (verified owner)

    I’d like to leave a positive review for the bypass kit I purchased for my 2008 Tundra a year ago. Upon installation (which was easy other than the plugs behind the engine block — those were not fun) my truck immediately left limp mode and all the dash lights went off. Recently (a year later) my dash lights showed limp mode codes again even though the truck was not in limp mode. I contacted Steve and he immediately sent me a replacement sensor which arrived the next day. I installed it in 20 minutes (no plugs necessary this time!) and all the lights are off again. Not only is this a great product, but the service that Hewitt provides with it makes it a must buy. I highly recommend the product and the seller.

  19. Jr Negron Auto Repair Orlando FL

    Had customer buy this for me to install and eliminate the pump from vehicle. We had Hurricane Ian come by and the pump had gotten water in it causing issue and vehicle went to limp mode. He ordered it on a Sunday late night and in Tuesday afternoon kit showed up to his door step via FedEx. Product was easily installed in 45 mins. Helped I read them online so that way I knew what to expect. Instructions were on point. Once installed I used scanner, cleared codes, started truck and power was present. No more limp mode. Customer extremely happy with how truck runs now. The kit did include plastic covers for power wires going to air injection drivers. Would probably make the kit include also terminal covers for the wires going to pump to avoid corrosion. I ended up taping them off when pump was removed. Over all would recommend this kit to anyone who wants to fix there vehicle without spending the $2000 at dealership. Vehicle was a 2008 Toyota Tundra 4.0L with 225,000 miles. Running strong!!!

  20. rpalmer.aaron (verified owner)

    2010 5.7 Flex Fuel Tundra, 92,000 miles. Had code P2442 and limp mode. The part took 2 days to arrive and fixed me right up. Highly recommend. However, and this was likely due to specific issues with my truck, but the install took about 4 hours and was definitely a two man job. Your mileage may vary but we had to get some obscure tools here and there and use some muscle. But it’s a 12 year old truck, so it’s to be expected. Regardless great product.

  21. jrsilvey1

    2008 Toyota Tundra with ~140K miles. P2442 error code. Ordered the Gen-2 kit. Highly recommended. Support was great by email and or phone service. High quality products. Instructions very thorough. Installed over a month ago and so far so good. Thank you again!

  22. davedish (verified owner)

    This Gen2 kit is the one to get if you are having problems with your Tundra’s Secondary Air Injection system. I was lucky when my issue cropped up: I just had a check engine light on; the truck managed to stay out of “limp-home” mode. When I got an estimate at the shop to bring it back to factory specs, they came back with $4500!! (mainly because of the time required to disassemble most of the engine to get to the parts in question. This kit was straightforward with outstanding instructions – and the check engine light immediately disappeared. While the connectors on the back of the manifold were a bit hard to get to – and significant leverage needed to be applied to the exhaust studs to slip those baffle plates under the pipes – a basic Wrenchhead should be able to install this kit with no problem. Great job Hewitt-Tech…saved me thousands!

  23. Dustin Patterson (verified owner)

    My 2007 5.7 Tundra was throwing P2443 (Secondary Air Injection Stuck Closed Bank 2.) Had a check engine for a month or so and then it went to limp mode. I did some research and found Hewitt Technologies and everything seemed legit. Fast shipping and a very well made product arrived. I did the install with block off plates in about 1.5 hours. That passenger side plug was a pain in the ass. My advice is to keep playing with different angles and different arms until you can get your hand on it. The block off plates went much easier than anticipated. Overall pretty straight forward, cleared my codes and truck is performing as it should now. NOTE: Super impressed with the product quality and attention to detail. Do not see that often.

  24. John Hicks

    All I can say is great company. I’ve purchase 2 of these gen 2 kits and their customer service is unlike any other.

  25. John (verified owner)

    2013 Tundra 4.6L, code p0419 secondary air injection bank B. Check engine light came on and hit it with the code reader. Next step took it by the shop and found out both pumps on passenger side were shot. Quoted me 3200.00 to fix the issue. Got to looking around and found this product Gen 2 bypass and decided to take the chance after reading the great reviews and I’m glad I did. Product got to me in 2 days and was everything advertised. Nicely packed and great instructions. Took about 1 hour with block off plates and no more codes. Thanks for this solution to those of us that don’t have 3200 bucks for emissions! Again thanks for your quality product.

  26. Michael Bower (verified owner)

    If there was a magic wand for SAIS repairs, it would be named after Hewitt Technologies. I installed the Gen-II SAIS Bypass and both Pressure Sensor Options (both PSOs due to a bad air switching valve on my 2008 Tundra 5.7L) and it wasn’t that difficult with their detailed instructions. As soon as I started the truck the check engine light was off and out of limp mode!

  27. Jared Evans (verified owner)

    2007 Tundra 4.7 with 68000 miles (yes low miles that is why i bought it) Back in February 2022 , engine light came on – ran the scan tool and came back with P2441 (bank 1 valve stuck closed). Started my research and learned about the Secondary Air design problem that Toyota created. Did further research on parts etc.. even learned about Hewett Tech at the time and decided to go another direction. Took my truck to a shop and had them validate my diagnosis. Replace the bad valve at $600+. Decided to do it myself and purchased a Dorman replacement valve from local autoparts store, cost 284+ for the valve (life time warranty what could go wrong???). Put that valve in and the truck ran great, engine light went off, all was good. Now March 24th, jump in my truck and i have the engine, VSC and Stability control lights all on. Connect my Scanner and getting a P2433,(Bank 1 valve pressure sensor is junk) clear the code, comes right back on. Truck running in limp mode. At this point i am frustrated and research again the whole issue. I decide to call Hewitt Tech. I give them a call, explain my situation, my codes and what I have done the past etc.. They give me all of the options, and their suggestions on what to do to fix the issues. They answered all of my questions and gave great customer support. I decided to go with the GEN 2 product and order it. It arrived 3 days later. I remove the valve that I already replaced and reinstall my “old” original valve (the old valve was stuck open by the sensor was still good). I then follow the directions provided (step by step) and install the GEN 2. The instructions were very well done, great pictures and understandable. with everything I had to do, it took me about 2 hours (1 hour was to replace the valve and block off plates). I took my time and install looks real clean (Hewitt did a good good with the wiring design). Hooked the battery back up and the truck run greats, no more lights, no more limp mood. Stay away from OEM and aftermarket parts on this issue, you will just be dealing with it again down the road. Learn from me and go with Hewitt Tech the 1st time.
    I highly recommend this product and company.

  28. justen calamayan

    I run a small auto repair shop all the way here in hawaii. Ive had 3 customers with limp mode issues all tundras. when given an estimate of 3-4k to address secondary air injection system using the factory parts/following Toyotas Technical service bulletins all have the same look/response. “wow thats expensive, “i need my vehicle for work”, “how am i going to afford this”. Being a trained auto technician, my gears start to turn and find ways to reverse engineer the system. What do you know, its been done. ive used both gen 1 and gen 2 kits. all easy to install. gen 2 especially!! THE CUSTOMER SERVICE WAS AMAZING. SHIPPING WAS LIGHTNING FAST! Did i mentioned i live in hawaii??.. PRIORITY OVERNIGHT, is LEGIT! ive ordered things at 11am hawaii time and received products from hewitt tech, the next day by 3pm. THE NEXT DAY!!!!! these guys are no joke with getting you back on the road. Real recognize Real… and HEWITT TECH IS THE REAL DEAL!! its easier to sell $100 overnight shipping then 4k dollars worth of parts and labor that possibly may go out in the future. DO YOURSELF A FAVOR, ADD ON A PRESSURE SENSOR!! WORTH THE MONEY AND HEADACHE, WHEN IN DOUBT, BUY ONE.
    THE GEN 2 KIT IS NEARLY PERFECT! BUT do have some recommendations,

    -have Add on drop down menu for PSO. that way its in the customers face instead of going on a different page.
    -automatically include the pressure sensors in the kit.
    -provide shop discounts on shipping at the very least
    -provide mounting bracket for PSO or maybe integrate something internally of module provided that deletes PSO so no need for add on.
    – Off road sticker notifying technician that bypass was installed.

    thank you very much for the great product and customer service!! truely a life savor!!

    • Paul Hewitt

      Justin, Thank you for leaving your feedback and recommendations we have considered some of these and are constantly working to improve.

  29. wgmartinjr (verified owner)

    I have a 2008 tundra. 192k miles 4.7L. Check engine light came on. Codes P2445, P2433 & C1201. Emailed Hewitt with my issues. Derek got back with me in about 2 hours the first time. And about the same on the next 3 emails. GREAT CUSTOMER SERVICE. Did not want to order incorrect parts so I called. Again, GREAT SERVICE. They confirmed what I needed and placed my order. 3 days later the parts are at my home. This solved all of my problems. Codes all gone. Just for fun I ran it up to 90mph. Yea, the power is back. Of course this mode is for off road. I’m a builder not a mechanic. I can change out a starter, alternator, the basics. I completed the repair in about 50 minutes and that included calling Hewitt and confirming the position of a sensor. Guys, follow the printed instructions and you’ll be done in under an hour. Hewitt make an awesome product and service that’s second to none.

    Happy North Georgia Tundra Owner

  30. Dave

    I bought a Gen II SAIS kit and a PSO for my 2007 Tundra from Hewitt Tech February of 2021 and just made time to do the install in Jan 2022. I’m not terribly mechanically savy but Paul’s system and instructions made the installation a breeze. The components are high quality; the installation instructions include photos of critical steps and are easy to follow. I would recommend this solution for any Tundra owner that is facing Secondary Air Injection System failure, it is an excellent fix with top-of-the-line support.

  31. Karl

    I can’t say enough good things about these guys. I bought the gen II for my truck and it has worked flawlessly with no check engine codes ever since install. I messaged the team shortly after install with some questions I had and they immediately answered those. A couple of weeks after install I did have some intermittent starting problems with my truck and reached out to the team since this was the only modification I did to my truck. They gave me clues on what may be causing the problem even though it most likely didn’t have anything to do with the install. It turned out it was the battery terminal connection. Even though visually they looked good and were secured it needed a good brushing on the terminals and wires to make the connection better. So in my defense it was still related to install but certainly not Hewitt-techs fault or their product. There product is amazing along with their customer service!!

  32. Zach O

    If your are having issues with your secondary air pump… buy this Kit!!! My truck was in limp mode and had all the bells and whistles. 4 lo, traction controll, rough idol… 200k miles and I don’t have 4k to fix these stupid pumps… (Before I go on… let me digress) I purchased a competitors product before doing my due diligence.. I was nervous because I’ve been scammed on the internet before, so I started digging.. yes, after I made my initial purchase (Doh) well, like I said I started to compare products and even websites and found a lot more happy customers with the Hewitt brand. So I reached out to both companies.. it was the day before or after Thanksgiving, so I left a voice mail with Hewitt and called the other guy… Phone disconnected (oh shit I thought. Not again) so I emailed and also called my credit card company and started a claim. Monday I called Hewitt again and talked with um… shit, I just remember he didn’t have a H in his name (side joke) he was very nice and explained the difference between the original product they sell and the new 2.0 version. After careful consideration I chose the 2.0 and I’m thrilled. The package was shipped that day and I received a tracking number. The instructions came in color which is extremely helpful.. and I loved that it had extra hardware and Zip ties. I followed the instructions and watched this video just to make sure I did it right.. and boom, after installing this part and the cover plates. My tundra is a beast again. If I had any advice for people installing that passenger side electronic clip.. I’d say grab your phone and record a small video of the firewall area. It’s extremely helpful to verify you’re unplugging the correct things. Well, good luck people.. this product and the customer service is awesome. I believe the fell in the phone said the guy in the video is the creator of the actual bypass system.. other guys just copied him.. maybe I’m wrong there. Either way!! Can’t go wrong.

  33. Bill Chamberlin (verified owner)

    Your Gen-ll SAIS bypass kit was easy to install and solved my otherwise expensive secondary air system problem! Your customer service is outstanding! Very few companies can claim that anymore. My %u201807 5.7L powered Tundra is happy again! Thank you!

  34. Jose v (verified owner)

    I have a Toyota Tacoma 2013 base model, by accident I squeezed a small vacuum hose going to the pump and It went into limp mode, likely it was near my house. I was annoying all the other drivers since I could not accelerate and keep up with traffic, it fell really bad. I found out about this bypass kit and I read all the wonderful reviews and I decided to pull the trigger and got a kit. It is been in my truck over a year now and I can strongly recommend this kit to all owners of a taco. And the best thing is made right here in the wonderful USA baby!,,,, it is worth every penny. If you love your Tacoma you should get this kit. Thanks Hewitt team for a wonderful and well made kit.

  35. Rodney Young (verified owner)

    Very easy to install on my 2007 4.6L Tundra. Took me just over an hour to install with plates and saved me time and money over fixing the SAIS. Highly recommend and well worth getting the Gen II since it emulates the whole system pretty much.

  36. Kelly McLauchlan (verified owner)

    I ordered the GenII kit on a tuesday around noon on my lunch break I received It on Trusday at 2:06 from fedEx It took 50 hours to my doorstep wow. I live in northern Alberta Canada. I installed it today took longer than .5 to 1 hour but that`s ok it was me. I do have a bullydog in my 2008 toyota tundra 5.7 I have around 412000 km that`s about 256000 miles on it. the codes came on before install I cleared them then I installed the GenII kit and fired it up and went and drove the shit out it and no codes so far. I drive an 1.5 to and from work so 3 plus hours aday. I am very very impressed with it so for. I can not thank you enough.

  37. Mike S (verified owner)

    Works like a charm! I had code p2438, in limp mode. I bought gen-II kit with the pressure sensor add on for my 2008 tundra 5.7. It only took a little over an hour to install with blocking plates start to finish. Thanks guys, we’re back rolling!

  38. Lee (verified owner)

    Shut up and take my money!!! Hardest part was unplugging the one on the passenger side. Literally in a prone position on top of the engine for good 30 min just to get one plug off. Put a thick blanket over the engine bay so I can lay on top of it. Finally got it off by using a telescoping mirror and a pick. $400 seems a lot of money but trust me, worth every penny.

  39. Jared

    Just bought a sequoia with 5.7 from a dealership. 24hrs after purchase the truck went into limp mode and threw a p2440 code. This seemed suspicious after purchasing the truck with no warranty from the dealership. they did not care or did nothing to help me. The repair bill was $3500 from a independent shop. Thank God that this bypass kit was available.

  40. Kevin Wilbourn

    At 10.5 years and 157k miles, I got the dreaded CEL and Traction lights with limp mode. Code pulled was 2442 on my 2011 Tundra 4.6L. (Bank 2 SAIS Valve stuck open).
    If it’s not clear, limp mode = bad shifting, horrible throttle response, rough idle, and about 6 MPG. I drove mine a minimal amount in this terrible state and ordered the bypass Gen 2 kit right away.
    5 stars aren’t enough to cover this product. The directions were fantastic, the product was packaged very well. I managed the install over my lunch break, and I’m a computer geek, not a mechanic. From what I’ve observed online, the 4.6 may be the easiest motor to install this kit on. You need a Phillips screwdriver and a 10mm socket, that’s really it.
    After the install, my truck runs great! Comfortable idle again, solid power and the fuel economy is better than it has been for some time. So glad I did the bypass kit rather than shelling out a lot more money to replace parts that are going to themselves wear out in a few more years.

  41. Susan

    Purchased the Gen 2 for our 2008 Sequoia. Easy to install, runs like a charm. We are in Canada, and the fees/duties were under $40CDN. Sure beat the $1800 repair quote anyday !! Thank you !!

  42. Jeremy R

    You’ve got to read this review.
    I have a 2018 Tundra crew cab. One of the things I have always done to my trucks is install a remote start. Well, one day I noticed the remote start was not allowing my truck to run after starting. It would start, self analyze and then self stall. It would go through this 3 times before shutting down. I thought I may have had a bad remote start kit and then I started to do research.
    The first time I heard the “vacuum cleaner” noise was when I was driving through Texas on a sub 30 degree day. I lost a lot of power and thought I got bad gas or it was the cold weather. Maybe the truck was made for hot weather?? Any way, I was able to make it home and in that time I NEVER got any trouble codes or dash lights.
    After reading about all of the people having problems with the SAIS, I decided to see if Toyota would fix it. They in fact had an extended warranty for many years in order to fix or replace the SAIS but I did not want them to pull the engine to fix these air injection motors because once an engine is pulled, it will never be the same.
    I think the fact the government INSISTS that vehicles have SAIS is sinister. Of course they are not our friends and I am not surprised that the government makes all vehicles be “50 state compliant” when it is really California that is making all these crazy emissions rules! OK.enough about politics.
    So, I read all of the reviews and I saw how expensive the GEN II bypass kit was, but several of y’all just said to bit the bullet and go for it. I am very glad I did! Even though my truck was not throwing codes simply suggests that the truck was using the SAIS system as intended. But, it was obviously still causing problems.
    INSTALL: I am a handy kinda guy but it still took me almost 3 hours. First hint is to work on your truck when it is cooled off! Finding the connections was easy, but getting the passenger side plug off and then plugging in the new one took an hour (damn big hands!) The second part was installing the exhaust intake plates. They are easy once you get the hang of it. The one thing I want to point out is on the video and in the directions, it shows that you need to remove the rubber shroud before you can access the ports. That is true for the passenger side, but on the DRIVERS side, exhaust port is closer to the firewall and there is an open area (no rubber shroud) FYI. I used a stick about 3/4″ in diameter to push up on the white metal tube behind the port. Get a stick about 22″ long, weave it through the engine and various hoses from under the engine. Once it is in place, I used a jack to gently lift these tubes and the plates easily slipped in.
    RESULTS: The first time I started my truck, it was much smoother. It has a nice throaty sound like it was designed, but it settled into a gentle purr rather than ramping up the RPM’s like it had been doing for the last year or so. I took it out on a test drive and I was able to scratch the pavement.I am telling you, the truck has not had this much power since I left the dealer. The next morning I used my remote start and the truck started up with no issues. Finally, I wanted to say that when I made a 10 hour trip down to Florida, I got 18.1 MPG running at 75 MPH and a smooth and consistent 2,000 RPM. I have NEVER gotten that good of gas mileage. The best I ever got was 17.6 MPG so that puts this as a 3% fuel increase. That is a 1/2 a mile per gallon increase.not much right? But with a 38 gallon tank, I will get an extra 19 miles which is about a gallon of fuel!!
    This device may not have been designed to increase fuel economy or make the truck run better, but I assure you, it did.
    Simply amazing and a pleasure doing business with you! Also, I got the device in the mail in two days. Fast, free shipping.

  43. Keith

    2010 Tundra 4.6L throwing SAIS trouble code. I’m handy but not a mechanic. The Gen II was easy-peasy to install and works as advertised. Well designed and manufactured, good installation documentation, and from what I can tell high quality materials. I discovered that when the ECM is cleared due to disconnecting the battery (which is part of the installation process)the engine dies after the first re-start and throws a P1604/1605 which, according to my research, will clear after the ECM relearns lost

  44. John Mullen


  45. Ronnie in KY

    I normally don’t write reviews but this product has cured my ailing tundra. the gentleman I spoke to was knowledgeable and helpful. the kit, literature, and instructions were dead on and had it installed on a cold winter day in about 30 – 40 minutes. It’s been on my tundra for over 3 months with perfect function. highly recommend it to anyone with this issue. saved $1800 in repairs and got rid of a reoccurring problem.

  46. Colton Estes

    Great product! Did the install in one afternoon no problem. Hardest part was working around this gut of mine!

  47. Susan

    Purchased to Canada for a 2008 Toyota Sequioa. Worth Every Penny, Easy to install, beat the $1800/quoted fee to replace all parts. Duties/Tax was only $35 Cdn

  48. BEM

    The Gen II SAIS has worked well for long enough that I feel comfortable saying that it was well worth the price. I have an 07 Tundra 4.0L and have had no CELs and no limp mode issues since installation

  49. Michael Bean

    I should have purchased the gen II kit from the start. took me 45 minutes to install and erase weeks of worry and pathetic response/power out of my 2010 Tundra. Drives like it should again! Don’t think, just buy one if you are also facing the same sais issues.

  50. Mark Franklin

    Wanted to wait before I posted a review. I have had this on for over a year now.No issues at all. The truck is running great. I would highly recommend this to anyone wanting a permanent fix to the air pump issue on the Tundra. Hewitt tech was very professional at helping me with the gen 2 bypass kit. Definitely buy this if you want to fix the issue.

  51. Oscar

    Highly recommended. quality products excellent customer service.