Gen 1: Secondary Air Injection System Bypass Kit (Plug & Play)

(68 customer reviews)


The Gen 1 (V36H) is compatible with most 2005 – 2007 models. It is our basic bypass kit that enables you to clear the Check Engine Light, Limp Mode and error codes related to mechanical SAIS faults. Bypass kit will include Block off Plate(s) and Starter Relay Wire.

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Hewitt Tech Generation 1 Secondary Air Injection System Bypass Kit (Plug & Play)
The Hewitt Tech (HT) Gen 1 Bypass Kit prevents operation of the SAIS at cold soak start. The Gen 1 is our basic bypass kit that enables you to clear the Check Engine Light, Limp Mode and error codes related to mechanical SAIS faults. The V36H is compatible with most Toyota and Lexus vehicles model years ’05 – ’07. The Plug & Play version of the Gen 1 Bypass kit offers all the same features and benefits of the Wired version but decreases labor/Install time with connectors compatible with the vehicle’s factory components. All wiring connections, except the starter relay wire, are achieved using the Plug & Play harness. 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. We recommend the Gen 1 Plug & Play Bypass kit for both professionals and DIY mechanics because of the ease of install and proven performance.

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 Mechanical Trouble codes the Gen 1 Bypass Kit typically addresses*:

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

The following are Trouble codes NOT addressed by the Gen 1 Bypass. These will require kit addon(s) in order to clear. However, if you are getting any electrical codes our recommended solution is the Gen 2 Bypass kit.

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

Electrical SAIS error codes are usually caused by an open or short circuit in one of the Air Switching Valves or Air Pumps. Each code would require a separate addon.

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 (IAT/MAF)
  • 2 x Secondary Exhaust Valve Block Off Plates (Engine Specific)
  • 1 x 10′ Piece of Violet 20 AWG TXL – Starter Relay Connection Wire
  • 1 x Printed Copy – Detailed Bypass Module Installation Instructions
  • 1 x Printed Copy – Block Off Plate Instructions (Engine Specific)


  • Bypass Wiring Harness:
    • Straight forward Plug & Play connections compatible with Factory components.
    • High Quality Automotive Engine Compartment Grade TXL Wiring
  • Bypass Module:
    • 4cm x 4cm x 1.4cm Black Duroplastic High Temp Enclosure – UL 94 V-0 Flame Resistance
    • Black Epoxy Potted for environmental and shock protection.
  • 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
  • Start Relay Wire:
    • ONLY available from Hewitt Technologies home of The Original SAIS Bypass Modules.
    • 10′ Piece of Violet 20 AWG TXL wire with female disconnect terminal.
  • 3M™ Automotive Acrylic Double-Sided Tape for mounting
  • Assembled 100% by hand in the USA!
  • Limited Life-Time Warranty


The bypass module is activated when the ignition is first switched to “ON” and any time it detects a 4-12V signal on the starter relay wire. The starter relay wire is only available from Hewitt Technologies home of the Original SAIS Bypass Modules! When connected, ensures that the module actively prevents the SAIS from running on EVERY start.

With the starter relay wire connected you can turn the ignition to “ON” for any period of time and the module will be active as soon as you crank the engine. Without the starter relay wire connection, you would need to turn the ignition back “Off” and then crank the vehicle to ensure the module is active or the system could operate and cause trouble codes and the CEL to come back on. Just install the kit with the starter relay wire connection and don’t worry about having to start the engine as soon as you turn the key on! If anyone else drives the vehicle this is a Must!

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 .8 lbs
Dimensions 7 × 5 × 1.5 in

2005, 2006, 2007


Lexus, Toyota


Tundra, Sequoia, 4Runner, Tacoma, Land Cruiser, Hilux, GX 470, LX 470


2.7L, 4.0L, 4.7L, 5.7L

68 reviews for Gen 1: Secondary Air Injection System Bypass Kit (Plug & Play)

  1. Joe DiDonato (verified owner)

    I am 72 years old and technically challenge, so this is the easiest way to for me to tell anyone who got a dreaded P1445 code that all is not lost. I just installed a gen 1 bypass on my 2007 Lexus GX470 and it was very easy, for me getting down to install the blocking plates was tough but again I am an old timer. The directions are great and easy to follow ,and tech help is just a call away and you get to talk to a human not a recording. Which brings me to the customer service and tech staff. You are a model of what a great company should strive for. You saved me well over $2000.00 and it was a pleasure doing business with yoh. Thanks

  2. David

    My fine 2006 DC Tundra, which I purchased new, was behaving poorly and I was faced with the all-too-common dealer service stuff to resolve the problem(s), and my mechanic found this unit and installed it. I’m at 326,000 miles and it’s running strong, with no issues whatsoever. Toyota should really revise their coverage with this issue. This truck was expensive !! Thank you Hewitt-Technologies !!

  3. Tim S.

    2007 Tundra-It was a super simple install & it finally made the light go away. The install for the actual module was less than a 5 minute process, I’ve still got to install the block off plates, but the light is CEL is gone. Two enthusiastic thumbs up from me.

  4. Rusty

    2010 Toyota sequoia 4.6 V-8, limp mode, codes,,you know the drill. Installed a GEN one kit and this rig runs better than It ever has!! I saved thousands thanks Hewitt tech

  5. Nick J (verified owner)

    I wanted to pass on my positive review of both the product and technical support. All my questions were answered promptly and the product does what it%u2019s advertised to do at a very reasonable price. Easy install and no more unnecessary check engine lights or limp mode. Thanks for all your help team.

  6. Banz (verified owner)

    Around 140k, my dash lit up like a Christmas tree. Toyota went good for what they said was a $2,500 repair. Now again at 245k, it happened again but intermittently. I had been intending to purchase this kit but didn’t get around to it until the condition became permanent. H-T came through! I ordered by their cut off time and received the kit the next day. Installation instructions were clear so it went quite quickly. Thank you much for offering a great solution to this issue.

  7. Jason Short

    2006 Tundra SR5, 4.7L V8, 130k miles — I installed this item last weekend after noticing a temporary ‘whirring’ noise at startup, which began a few weeks ago. Never got to the point of a failure or a CEL, but this has now disabled the SAIS, stopped the noise, and I won’t have to worry about this defect in the future. It’s worth every penny. Lastly, the kit arrived quickly and was very easy to install. Thank you!

  8. Antonio S

    I installed the module on my 2007 Tundra and it runs without drama. Toyota did the warranty repair years ago so I know this would have cost big bucks at the dealer. The SAIS plug & play kit was easy to install and videos on youtube got me beyond my hesitancy. Thank you for a great product that really works.

  9. Tom Walker

    Had issues with my sai check valve took it apart found part of a seal stuck in it. Took it out put it back together and was fine. Month or so later the sensor went bad. I emailed them the code they said I would need the bypass and a jumper kit. I ordered it got my package a few days later. After driving with a top speed of 60 downhill with the wind pushing I was excited as a kid on Christmas to see it on the steps. Took about 30 minutes to install and was super simple to do. Jumped in the cab and started it up and no lights. Drove with no issues. So happy I found Hewitt-tech. Thank you for fast response and a very very simple to install product. 07 Tundra base 4.0 105,xxx. Thank you

  10. Alan Edwards

    THANK YOU, THANK YOU, THANK YOU Now I don’t want to drive my truck into a tree.

  11. Justin Bora

    *HT Response – We try to make sure owners are fully aware of this before purchasing. However, unless you called to place the order we have to rely on our website to convey the information. This is why it is clearly mentioned and the possibility warned about on the V36H product pages. There is also a full write-up about it on our codes page and how to get around the problem if you have one of the affected vehicles. The freezing temperature P2445 ECM glitch is a known issue with some of the older 4.7L vehicles. The unit is still preventing your system from running like it is supposed to it just can’t stop a glitch in the ECM.

  12. Marvin Phillips

    My 2005 toyota tundra went into limp mode after engine light came on for secondary air injection system. Mechanic wanted thousands to fix.Done some research and watched some videos on Hewitt bypass system . Decided to purchase took me about a hour to install. Absolutely the best product out there.saved me alot of money and my truck runs great again .

  13. Scott Townsend

    Thanks Hewitt Tech! Professional job from start to finish. Another satisfied customer here just wanting to thank you.

  14. David

    Easy to install. Passed the stringent California Smog Inspection in flying colors. Grateful for the practical solution it provides to what would be a very expensive problem.

  15. Shawn Hillman

    I have been installing these kits for years. They work great and have yet to have any customers have issues. Customer support is great.

  16. Franklin Van Horn

    Purchased this by pass for my 07 tundra with approx 200k on it, took me longer to find my 10mm socket than it did to install. amazing product. Everything it said it was. I do wish the jumper was about 2 feet longer so i could hide it better but still a 5 star product. Thank you

  17. John M

    Fabulous product!

  18. Dustan Hollifield

    I found out about Hewitt Tech after i had ordered the air pump and decided to give it them a shot. I really didn’t want to pull the intake and take the chance of messing something else up. I ordered the kit on Monday and received it on Thursday. I installed it the same day. My install time was about 35-40 min. As of right now i have not had any codes pop up or the vehicle go into limp mode but it jas only been a few days. Time will tell but it is looking like this was defiantly the correct choice.

  19. Timothy W Rodriguez

    2005 SR5 4.7L, If you are on the fence about this bypass kit, get off the fence and get install it and celebrate getting your Tundra back. It is an awesome alternative to taking it to the dealership or anyone else for that matter. All the best Timothy Miami/Florida

  20. Mark Schaffner

    I have a 2007 Toyota Tundra with a 4.7L. I had a code PO418, with an engine service light on. I check with the local Toyota dealership and aftermarket parts and found that the air injection pump is very expensive. I starter checking on the web and ran across a forum that talked about a bypass kit. I call and talked to Becky and she was very helpful in explaining how the kit should be installed. I was very surprised at how she had an answer to all my questions. I order the Gen II kit and it took almost 1 hour to install (I just took my time). After I installed it, I went and connected the battery and started the engine and BAMB!!! the engine light went off and the engine runs great. I didn’t even have to clear the codes. Thanks again for a great product. I will make sure that I will tell everyone how great this product is!

  21. Cameron Bragg

    AMAZING customer service! I ordered one for my wife’s 06 4runner. I put it on in under an hour, no problem. A month later I and my buddy are having to replace the starter. We accidentally knock one of the sensor connectors loose when we put the intake back on. The sensors were brittle and broke coming off. The truck starts throwing weird error codes about sais system/pressure. Well I know I’ve got all that bypassed. So I email these guys and tell them I replaced the starter, got the code do they have any ideas? And also while I’m in there should I remove any of that hardware since it’s bypassed by their kit. This was at 6 pm on a Saturday. Within an hour they had emailed me back. TWICE!

  22. Dan Steingraber

    I purchased the plug-and-play version for my 2007 Lexus GX470 that had the loud fan noise, and quickly coded up and went into limp mode. After a long search and a lot of reading, I decided to give the bypass a try. With the help of Becky at Hewitt Tech, I confirmed the part # needed, ordered with Fed-Ex next day delivery. The installation instructions are spot on and the install overall went smoothly. The only issue I had was due to rusted flange bolts. Use extreme caution with these, if you strip or break the studs any cost savings for the bypass will be lost!! Luckily a lot of PB blaster, a propane torch, and a socket meant for stripped bolts saved the day. Thank you Hewitt Tech for making a wonderful product and having excellent sales & service help. I can’t give the product enough stars!!

  23. Bruce McGowan

    After encountering limp mode with check engine, VSC and TRAC lights illuminated, diagnostic scan revealed the dreaded P2445 code, the Dealership wanted $1400 to fix the SAIS fault. They said that was a reduced price because they had just needlessly replaced front pads and rotors after I had told them it was the REAR brakes that needed attention (sound familiar?). Anyway, that amount to invest in a 12 YO vehicle with 200k miles, makes you think (knowing it will probably be more when the final bill lands). When researching the P2445 code, I came across the Hewitt bypass kit, plug and play for the 4.7. Read all reviews and ordered the kit. About 15 min after placing my order, I recieved a call from a very pleasant young woman verifying my shipping method and letting me know that due to the Labor Day holiday, my order would be delayed and did I want to change my shipping preference. This kinda surprised me as you rarely get a courtesy call from any online retailer. She wanted to make sure I understood the shipping dates and wanted me to be aware of the delivery date. Anyway, the kit arrived one day early because I think that young lady went the extra mile to insure my kit shipped as fast as possible. When the kit arrived, I installed in about 2 hours (I’m in my 70s). As others have said, it’s easier to install the cut off plates with the wheels removed.remember to be safe and use jack stands. The rest of the installation was basically plug/play. The wiring loom on the kit is very professional and, under closer inspection, I saw what I thought was corrosion on the female connector of the remote starter wirecloser inspection revealed not corrosion but DIELECTRIC grease. Right then I knew this was a quality product and was above and beyond what you normally expect and it let me know that whomever built this kit wanted it to last a long time. I know I’m rambling but I’m retired and that’s what we do. The kit worked flawlessly, code was extinguished and were rolling at full power again. Toyota makes a wonderful product and they last forever with the routine service (my other 2006 Sequoia has 400k ). Anyway, buy this kit, it’s a quality product with super technical support.

  24. Chris Napoleon

    Best thing I ever did! Installed this in about 30 mins. Erased all the codes with my OBD-II scanner. Works like a charm!!! Here in Alaska, the dealer wanted 6k for the system to be replaced. This was a total lifesaver! Thank you!!!!

  25. Mark

    About a year ago my out of warranty 5.7 tundra went into limp mode, dealer was at 4K, my local trusted mechanic said he would do for about 3k. Short research on the google and came up with this kit, called and talked to very nice women who sent me the goods, after install all Christmas lights went out, truck runs great. Little intense getting the blocking plates in, otherwise easy money. Got the state emissions letter last week, took truck in for the test and passed with zero problems. Win win!

  26. Johnny Johnson

    It was ok

  27. Steven McQueen

    I called Hewitt, A young lady answered the phone, I told her what was going on, she gave me the part number I needed. I ordered it got it in a couple of days. I followed directions that came with it(very easy to follow)I was about 40 minutes from start to finish. Thank you so much for a wonderful product that works like a charm.

  28. Ethan E

    Fantastic product! Ordered the plug & play for 2006 limited DC and it worked perfectly. Ordered on a Friday afternoon and had it Monday! Easy to install. The plates are a little more difficult but only because of location. The PB blaster is worth the 5$ made the screws come off by finger once bolt is loose. Only tool needed was a small ratchet with 10mm deep socket. Less than 300$ for everything needed saved me a couple thousand!!!!

  29. Beau Minch

    I bought this for my 07 tundra it works just fine god bless you people thank you

  30. Dave Pucklavage

    Fixed the problem. Easy install for wiring. Great service, get right back to you when you have questions. 5 stars THANK YOU for saving me money!!!

  31. chad

    My 2007 Tundra runs perfect now!! No limp mode, no check engine lights, nothing! Thank you! I don’t ever leave reviews, but this deserved one! They where extremely polite and helpful on the phone as well.

  32. Jorge Negron

    Had a customer come to me asking about fixing his Toyota Tundra. Had no power whatsoever. Did research online and found out about this kit. I was skeptical at first but this was a lot cheaper than an OE fix. Man, I was blown away. This really did the trick. The customer is so happy with his performance he told his buddies who have spent the $2000.00 at the dealership to rectify the same issue. I will definitely use this product in the future as an alternative to factory fix. Definitely worth the money!!!!

  33. Jim S

    Out-Freaking-Standing! I ordered the Plug & Play kit for my 2005 Tundra, received it in the mail today & got it installed. Worked perfectly so far. Be careful on the older models, as warned, the studs on the exhaust can be brittle. I had one break on me, so the install took a little longer than 1/2 hour. The instructions were great! the longest part of the job is deciding how you want to run the Purple wire. Thank you for a simple solution to a ridiculous problem! Great Job!

  34. Guido

    Bought the plug and play kit for my 2006 GX470 after I got the P14441 and P1444 errors and limp mode. Worked as advertised. Error codes and limp mode gone. Saved a lot of money vs the OEM fix for a 12 year old truck. Satisfied.