Secondary Air Injection System Air Flow/Pressure Sensor Circuit High Bank 2
P2438 indicates the secondary air injection system's air flow or pressure sensor circuit is reading higher than expected on Bank 2. The secondary air injection system injects fresh air into the exhaust to reduce emissions during cold start and idle, and this code signals a sensor or circuit malfunction preventing proper system operation.
What You Might Notice
- Check engine light illuminated
- Engine stalling at idle
- Difficulty starting the engine
- Secondary air injection pump making unusual noise
- Poor engine performance and rough idle
Most Common Causes
- 1
Faulty air pressure sensor
The air pressure sensor in the secondary air injection system may be defective or degraded, sending abnormally high voltage signals to the PCM.
- 2
Defective secondary air injection pump
The air pump itself may be failing or producing incorrect pressure that causes the sensor to read high values.
- 3
Faulty one-way check valve
A stuck or leaking check valve can allow backpressure into the system, causing inaccurate pressure sensor readings.
- 4
Wiring or connector issues
Corroded, damaged, or loose wiring and connectors in the secondary air injection circuit can cause signal problems and high voltage readings.
How to Diagnose It
- 1
Check Faulty air pressure sensor — The air pressure sensor in the secondary air injection system may be defective or degraded, sending abnormally high voltage signals to the PCM.
- 2
Check Defective secondary air injection pump — The air pump itself may be failing or producing incorrect pressure that causes the sensor to read high values.
- 3
Check Faulty one-way check valve — A stuck or leaking check valve can allow backpressure into the system, causing inaccurate pressure sensor readings.
- 4
Check Wiring or connector issues — Corroded, damaged, or loose wiring and connectors in the secondary air injection circuit can cause signal problems and high voltage readings.
How to Fix It
- 1
Test and replace air pressure sensor
Use a multimeter to check the sensor voltage output with the engine running. If readings are consistently high or out of range, replace the sensor with a new unit.
- 2
Inspect and repair wiring and connectors
Check all wiring and connectors in the secondary air injection circuit for corrosion, damage, or loose connections. Clean connectors with electrical contact cleaner and repair or replace damaged wiring.
- 3
Replace secondary air injection pump
If the pump is not operating correctly or producing abnormal pressure, replace the entire secondary air injection pump assembly.
- 4
Replace one-way check valve
Inspect the check valve in the air injection line for sticking or leaking. Replace the check valve if it is not functioning properly or allowing backflow.
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