Technical Description of OBD-II Trouble Code
The range/performance of the circuit for the secondary air injection system air flow/pressure sensor in Bank 1 is not within the expected values.
What does that mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and is applicable to many OBD-II vehicles manufactured from 1996 onwards. This includes vehicles from various manufacturers such as Buick, Chevrolet, Cadillac, Lexus, Toyota, BMW, Subaru, and others. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
The OBD-II trouble code P2431 and related codes P2430, P2432, P2433, and P2434 are associated with the circuit for the secondary air injection system air flow/pressure sensor in Bank 1.
The purpose of the circuit for the secondary air injection system air flow/pressure sensor in Bank 1 is to reduce the amount of hydrocarbon exhaust emissions during engine start-up in cold weather conditions. The Power Control Module (PCM) activates the air pump to supply pressurized fresh air, which helps accelerate the catalyst operation and reduce harmful exhaust gas levels. This process also helps the engine reach its normal operating temperature faster. The air system pressure sensor is used to monitor the pressure at the inlet of the air control solenoid valve, which opens and closes the valve based on predetermined temperatures and pressures recommended by the manufacturers.
When the PCM detects voltage or resistance outside the normal expected range in the circuit for the secondary air injection system air flow/pressure sensor in Bank 1, it sets the code P2431 and may illuminate the check engine light.
If your engine has multiple banks of cylinders, Bank 1 refers to the bank that contains cylinder #1.
Components of the secondary air injection system:
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 malfunction. Several symptoms associated with this trouble code can make driving the vehicle extremely hazardous.
What are some of the symptoms of the code?
Symptoms of a P2431 trouble code may include:
What are some of the common causes of the code?
Causes for this P2431 code may include:
What are some P2431 troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB’s) for the specific vehicle based on its year, model, and power plant. In some cases, this can save a lot of time by providing guidance in the right direction.
Depending on the specific vehicle, this circuit may include several components such as the secondary air injection pump, check valve, pressure sensor, air control valve, and the PCM. Conduct a thorough visual inspection to check the associated wiring for any obvious defects such as scraping, rubbing, bare wires, or burn spots. Next, check the connectors and connections for security, corrosion, and damaged pins. This inspection should cover all wiring connectors and connections to all components, including the PCM. Consult the specific technical data for the vehicle to verify the circuit configuration and confirm all components incorporated within the circuit, which may include a fuse or a fuse-able link. Test the check valve to ensure that the airflow is in one direction only. The presence of ice in the secondary air injection pump during extremely cold weather conditions indicates a defective one-way check valve that allows condensation from the exhaust to enter the pump.
Advanced Steps
The advanced steps are highly specific to the vehicle and require advanced equipment for accurate performance. These procedures involve using a digital multimeter and referring to the specific technical references for the vehicle.
Voltage Checks
The reference voltage and acceptable ranges may vary depending on the specific vehicle and circuit configuration. The specific technical data will include troubleshooting charts and the appropriate sequence to follow for an accurate diagnosis.
If this process identifies the absence of a power source or ground, continuity testing may be required to check the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power removed from the circuit, and the normal readings for wiring and connections should be 0 ohms of resistance. Resistance or lack of continuity indicates faulty wiring that is open, shorted, or corroded and must be repaired or replaced.
What are some common repairs for this code?
Common Mistake
We always recommend seeking professional service to address this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
