P2438 Secondary Air Injection System Air Flow/Pressure Sensor Circuit High Bank 2
OBD-II Trouble Code Technical Description
Secondary Air Injection System Air Flow/Pressure Sensor Circuit High Bank 2
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Buick, Chevrolet, Cadillac, Lexus, Toyota, BMW, Subaru, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
OBD-II trouble code P2438 and related codes P2435, P2436, P2437, and P2439 are associated with the secondary air injection system air flow/pressure sensor circuit bank 2. Bank 2 is the side of the engine that does not contain cylinder #1.
The purpose of the secondary air injection system air flow/pressure sensor circuit bank 2 is to reduce the amount of hydrocarbon exhaust emissions during engine start-up when the weather conditions are cold. The Power Control Module (PCM) activates the air pump to supply pressurized fresh air to accelerate the catalyst operation reducing the level of harmful exhaust gas. This process also allows the engine to reach the normal operating temperature faster. The air system pressure sensor is used to monitor pressure at the air control solenoid valve inlet to open and close the valve at predetermined temperatures and pressures based on the manufacturers' recommendations.
When the PCM detects voltage or resistance that is too high above the normal expected value range, within the secondary air injection system air flow/pressure sensor circuit bank 2, code P2438 will be set and the check engine light may be illuminated.
Secondary air injection components:
What is the severity of this DTC?
The severity of this code can vary tremendously from moderate to severe depending on the specific symptoms of the malfunction. Several symptoms of this trouble code could make driving the vehicle extremely hazardous.
What are some of the symptoms of the code?
Symptoms of a P2438 trouble code may include:
Engine may stall at idle Engine may not start Secondary air injection system making noise Poor engine performance Check engine light illuminatedWhat are some of the common causes of the code?
Causes for this P2438 code may include:
Defective secondary air injection pump Faulty one-way check valve Defective air control solenoid valve Defective air pressure sensor Faulty or damaged wiring Corroded, damaged or loose connector Defective PCMWhat are some P2438 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 by year, model and power plant. In some circumstances, this can save a lot of time in the long run by pointing you in the right direction.
Based on the specific vehicle, this circuit may incorporate several components including the secondary air injection pump, check valve, pressure sensor, air control valve and the PCM. Perform a thorough visual inspection to check the associated wiring for obvious defects such as scraping, rubbing, bare wires, or burn spots. Next is to check the connectors and connections for security, corrosion and damaged pins. This process must include all wiring connectors and connections to all components including the PCM. Consult the specific tech data for the vehicle to verify the configuration of the circuit and confirm every component incorporated within the circuit which may include a fuse or a fuse-able link. The check valve should be tested to ensure that the airflow is in one direction only. Ice in the secondary air injection pump during extremely cold weather conditions is an indication of a defective one-way check valve allowing condensation from the exhaust t
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