What Do My Secondary Air Injection Error Codes Mean?

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I have Good News and Bad News. The Good News is that you are not the only one tripping Secondary Air Injection (SAIS) Codes. The SAIS is notorious for failing and as you have researched a very common issues for 4Runners. You already know the Bad News, you Check Engine Light is on and most likely going into Limp Mode.

The following includes details from our Blog "What Do My SAIS Error Codes Mean?". We hope this information will help you better understand the failure prone system and if you have any question do not hesitate to contact us on the forum or through our website.

Types Of Secondary Air Injection Failures And Error Codes
There is a limited set of DTCs the secondary air injection system can trip. We have categorized them into three types of failures: mechanical, electrical, and pressure sensor. This is important to note because Hewitt Tech bypass kits only cover certain codes, and kit add-ons may be required to address other SAIS codes.

Please know that neglecting SAIS error codes, repeatedly clearing them, and driving your vehicle can lead to further damage. This includes damage to the factory wiring harness or the engine control module (ECM). The Hewitt Tech bypass kit will not address this damage.

Listed below are the most common SAIS error codes that can typically be addressed by the Hewitt Tech bypass kit or bypass kit with an add-on. To confirm code coverage, please refer to Bypass Kit Comparison Chart or specific product listing.

Mechanical Codes*
Mechanical codes relate to the moving components of the SAIS. For example, if the air pump fan is malfunctioning or the air switching valve is stuck, one of the following codes will appear:

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*
Electrical codes indicate an issue with the circuit within the SAIS components. Each air pump and air switching valve has an electrical circuit. The following codes are usually caused by an open or short in these circuits:

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

Pressure Sensor Codes*
The following codes are directly associated with damaged pressure sensor(s). This is commonly caused by an air switching valve being stuck open, which exposes the pressure sensor to exhaust. The following codes will put the vehicle into “limp mode” and will not clear until addressed:

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

What Causes The Secondary Air Injection System To Fail?
It’s no secret that secondary air injection systems on Toyota and Lexus vehicles are prone to failure. As detailed above, the primary reasons for error codes are mechanical, electrical, or pressure sensor faults. Many factors contribute to these failures, including moisture entering the system, air pump debris, carbon buildup, and general wear and tear.

Please clink on the Link above to continue reading about...

• Other Reasons SAIS Codes Are Tripped
• Other Common Codes

Additional Secondary Air Injection Resources
To learn more about what is the SAIS or SIAS solution click on the following “Must Read” Hewitt Tech Threads:

- What Does the Secondary Air Injection System Do?
- How to Fix the Secondary Air Injection System?
***Spoiler Alert - Don't Use Aftermarket Parts***

Disclaimer
It is illegal to remove, dismantle, or otherwise cause to be inoperative any pollution control device required by federal, state, or local emissions law. No other applications are intended or implied.

 

Well written, beautiful explanation here. Thanks for sharing.

 

I installed the Gen II on my 06 V8. I am now in the middle of replacing my starter. I have two questions for the Hewitt-Tech guys:

1. When I installed the bypass system my previously installed Scangauge no longer shows any info, it has power to it but no readouts.
2. Since installing the bypass system, can I go without reinstalling the SAIS components? pump, switching valves, etc.

Thanks for your input!

 

The Gen 2 Bypass Kit will allow you to remove the Air Pump. However, if you wanted to remove the Air Switching Valve you will need to unbolt the Pressure Sensor that is attached to it. It is the component connected to the factory wiring harness with the vacuum line running to it. That must remain plugged in because the ECM is still reading that sensor. Feel free to give us a call it would be much easier to explain over the phone.