The P2431 error code reads “AIR / AIR (Bank 1) AIR / Pressure Sensor Circuit Performance Range Mismatch”. Often, in programs working with an OBD-2 scanner, the name may have the English spelling “Secondary Air Injection System Air Flow / Pressure Sensor Circuit Range / Performance (Bank 1)”.
P2431 datasheet and explanation
The P2431 code refers to a secondary air injection system that pumps outside air into the exhaust system when the engine is cold started. This extra air helps burn the very rich exhaust gases that are generated when the engine is warming up.
The secondary air injection system is based on either a belt or an electric pump. The pump pumps ambient air into the engine exhaust system to reduce emissions.
Heat-resistant silicone hoses are used to supply cold outside air to the pump. The ambient air is filtered before being sucked in through an air filter housing specially designed for the secondary air injection system.
Ambient air is fed into the exhaust system through high-temperature silicone and steel pipes connected to openings in the exhaust pipes. One-way check valves are installed in each exhaust hose to prevent condensation from entering the pump and causing malfunction.
The PCM controls the operation of the secondary air injection pump based on engine temperature, RPM and throttle position.
The air system pressure sensor is used to monitor the inlet pressure of the air control solenoid valve. To open and close the valve at specified temperatures and pressures in accordance with the manufacturer’s recommendations.
If the PCM detects a voltage or resistance performance range mismatch in the secondary air injection system air flow / pressure sensor circuit. P2431 will be stored and the Malfunction Indicator Lamp (MIL) may illuminate.
On some vehicles, the pressure sensor is part of the air flow control solenoid valve.
The primary driver symptom of a P2431 code is a MIL (Malfunction Indicator Light) illuminated. It is also called Check engine or simply “check is on”.
They can also manifest as:
- The control lamp “Check engine” on the control panel will light up (the code will be written into memory as a malfunction).
- On some European vehicles, the pollution control warning light comes on.
- Noise from the air pump due to mechanical wear or foreign objects in it.
- The engine accelerates poorly.
- The engine stalls or does not start well.
- Floating revs, as well as attempts to stall at idle.
- Sometimes symptoms may not be present despite a stored DTC.
Error severity P2431 ranges from moderate to severe depending on the specific symptoms of the malfunction. In some cases, driving with this fault can be extremely dangerous.
Reasons for the error
The P2431 code may indicate one or more of the following problems have occurred:
- Secondary air injection pump defective.
- The pump check valves are out of order.
- Defective secondary air pump relay.
- Control solenoid problem.
- Air pressure sensor defective.
- Moisture intrusion into pump and motor.
- Breakage or interruptions in the supply of power to the secondary air injection system.
- Blown secondary air injection system fuse.
- Sometimes the cause is a faulty PCM.
How to Repair or Reset DTC P2431
Some suggested steps to troubleshoot and fix the P2431 code:
- Connect the OBD-II scanner to the vehicle diagnostic socket and read all stored data and error codes.
- Repair any other errors present before continuing to diagnose the P2431 code.
- Visually inspect the electrical wires and connectors associated with the secondary air injection system.
- Repair or replace any shorted, interrupted, damaged, or corroded components as necessary.
- Check the secondary air injection pump.
- Test the air pressure sensor.
Diagnostics and problem solving
The first step in troubleshooting P2431 is to review the vehicle-specific Technical Service Bulletins (TSB). In some cases, it can save you a lot of time by directing you in the right direction.
Next, you need to check the electrical, which includes the secondary air injection pump, check valve, pressure sensor, air control valve and PCM. Carry out a thorough visual inspection of the wiring for obvious defects.
Then check the connectors and connections for safety, corrosion and damaged pins. This process should include all circuit connectors and connections to all components, including the PCM.
Check the non-return valve to make sure the air flow is in one direction only. Condensation is a sign of a defective one-way non-return valve allowing it to enter the pump from the exhaust gas.
If the air pump does not turn on, check all relevant fuses, relays, wiring, and pump motor for continuity. Replace or repair defective components as necessary.
Continuity tests should always be performed while disconnected from the supply circuit. Normal resistance readings for wiring and connections should be 0 ohms.
Resistance or lack of continuity is a sign of faulty wiring, open circuit, short circuit, or corrosion that needs to be repaired or replaced.
If all tests pass and the P2431 code continues to appear, there is most likely a secondary air injection pressure sensor malfunction. But a PCM malfunction should also not be ruled out until the pressure sensor has been replaced.
On what cars does this problem occur more often?
The problem with the P2431 code can occur on different machines, but there are always statistics on which brands this error is more common. Here is a list of some of them:
- Chevrolet (Chevrolet Impala, Cobalt, Trailblazer)
- Dodge (Dodge Stratus)
- GMC Envoy
- Lexus (Lexus lx570)
- Pontiac (Pontiak Grand Prix)
- Saturn (Saturn Ion)
- Subaru (Subaru Impreza)
- Toyota Land Cruiser
- Volkswagen (Volkswagen Jetta, Passat)
Other errors can sometimes be found with DTC P2431. The most common are the following: P0411, P2430, P2432, P2433, P2434, P3433.