P2438 Secondary air injection system air flow / pressure sensor circuit, bank 2

P2438 Secondary air injection system air flow / pressure sensor circuit, bank 2

OBD-II DTC Datasheet

Secondary Air Mass / Pressure Sensor Circuit Bank 2

What does this mean?

This is a Generic Powertrain Diagnostic Trouble Code (DTC) applicable to many OBD-II vehicles (1996 and newer). This may include, but is not limited to, Buick, Chevrolet, Cadillac, Lexus, Toyota, BMW, Subaru, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration. ...

OBD-II DTC P2438 and related codes P2435, P2436, P2437 and P2439 are related to the secondary air injection system flow/pressure sensor circuit bank 2. Block 2 is the side of the engine that does not contain cylinder #1.

Block 2 of the air flow / pressure sensor circuit of the secondary air injection system is designed to reduce the amount of exhaust hydrocarbons released when the engine is started in cold weather conditions. The Power Control Module (PCM) activates the air pump to deliver compressed fresh air to speed up the catalyst, reducing harmful exhaust gases. This process also allows the engine to reach normal operating temperature faster. An air system pressure sensor is used to monitor the inlet pressure of an air control solenoid valve to open and close the valve at specified temperatures and pressures as recommended by the manufacturers.

When the PCM detects that the voltage or resistance is too high above the normal range of expected values, the secondary air injection system, bank 2, air flow / pressure sensor circuit will set a code P2438 and the engine light may illuminate.

Secondary air supply components:

What is the severity of this DTC?

The severity of this code can vary greatly from moderate to severe depending on the specific symptoms of the problem. Some of the symptoms of this DTC can make driving extremely dangerous.

What are some of the symptoms of the code?

Symptoms of a P2438 trouble code may include:

• Engine may stall at idle
• Engine won't start
• Secondary air injection system makes noise
• Poor engine performance
• Check engine light is on

What are some of the common causes for the code?

Reasons for this P2438 code may include:

• Secondary air injection pump defective
• Check valve defective.
• Defective air control solenoid valve
• Air pressure sensor defective
• Faulty or damaged wiring
• Corroded, damaged or loose connector
• Defective PCM

What are some steps to troubleshoot the P2438?

The first step in troubleshooting any problem is to review the vehicle-specific Technical Service Bulletins (TSBs) by year, model, and powerplant. In some cases, this can save you a lot of time in the long run by pointing you in the right direction.

Depending on the specific vehicle, this circuit may include several components, including a secondary air injection pump, check valve, pressure sensor, air control valve, and PCM. Perform a thorough visual inspection to check the associated wiring for obvious defects such as scratches, abrasions, bare wires, or burn spots. Next, you should check the connectors and connections for safety, corrosion and damage to the contacts. This process should include all electrical connectors and connections to all components, including the PCM. Consult your vehicle specific datasheet to verify the circuit configuration and confirm each component included in the circuit, which may include a fuse or fuse. The check valve should be checked to ensure that the air flow is in one direction only. Icing in the secondary air injection pump in extreme cold weather indicates a malfunction of the one-way check valve allowing condensate from the exhaust gas to enter the pump.

Advanced steps

The additional steps become very vehicle specific and require appropriate advanced equipment to be performed accurately. These procedures require a digital multimeter and vehicle-specific technical reference documents.

Voltage test

The reference voltage and allowable ranges may vary depending on the specific vehicle and circuit configuration. Specific technical data will include troubleshooting tables and appropriate sequence of steps to help you make an accurate diagnosis.

If this process detects that a power source or ground is missing, a continuity test may be required to verify the integrity of wiring, connectors, and other components. Continuity tests should always be done with power disconnected from the circuit and normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates a wiring fault that is open, shorted, or corroded and needs to be repaired or replaced.

What are the standard ways to fix this code?

• Replacing the secondary air injection pump
• Replacing a defective one-way check valve
• Replacing the air pressure sensor
• Replacing the air control solenoid valve
• Cleaning connectors from corrosion
• Repair or replace faulty wiring
• Flashing or replacing PCM

General error

• Replacing the secondary air injection pump when a bad one-way check valve or bad wiring causes this PCM to set.

I hope the information in this article has helped you point in the right direction to troubleshoot a Secondary Air Injection Air Flow / Pressure Sensor Circuit DTC problem, Bank 2. This article is for informational purposes only, and specific technical data and service bulletins for your the car should always take priority.

Related DTC discussions

• Help P2438 on my 2007 TundraI am trying to locate the top row 2 of the secondary air injection flow / pressure sensor circuit. Can anyone point me in the right direction? Thank you Gebby43 ... 

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