Secondary Air Injection System Flow/Pressure Sensor Range/Performance (Bank 1)
The P2431 code indicates that the Engine Control Module (ECM) has detected a malfunction in the secondary air injection (SAI) system's air flow/pressure sensor circuit on Bank 1. This sensor monitors the air pressure or flow in the SAI system, which injects fresh air into the exhaust to reduce emissions during cold starts. The ECM compares the sensor reading to expected values; if the signal is out of range or performance is degraded, it sets this code. Common causes include a faulty sensor, wiring issues, or a blocked SAI system.
1. Most Common Causes
- Faulty secondary air injection pressure sensor
- Wiring or connector issues in the sensor circuit
- Blocked or leaking secondary air injection system components (pump, hoses, valves)
- Failed secondary air injection pump or relay
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test
- Rough idle or hesitation during cold start
- Possible reduced fuel economy
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P2431 and check for related codes.
Step 2: Visually inspect the SAI pressure sensor, wiring, and connectors for damage or corrosion.
Step 3: Test the sensor signal voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check the SAI system for blockages or leaks by activating the pump and monitoring pressure.
Step 5: If sensor and wiring are OK, test the SAI pump and relay operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but it may cause increased emissions and potential failure of emissions tests. The vehicle may also experience rough idle or hesitation during cold starts. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement. If the SAI pump or other components need replacement, costs can be higher ($200-$500+).
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.