Reductant Injection Air Pressure Control Valve Circuit/Open
The P20A6 code indicates a problem in the reductant injection air pressure control valve circuit, which is part of the selective catalytic reduction (SCR) system. This valve controls the air pressure used to inject diesel exhaust fluid (DEF) into the exhaust stream. An open circuit means there is a break in the electrical path, preventing the valve from operating correctly. This can lead to insufficient DEF injection, causing increased NOx emissions and potential damage to the SCR system.
1. Most Common Causes
- Faulty reductant injection air pressure control valve
- Open or shorted wiring in the valve circuit
- Corroded or damaged electrical connectors
- Blown fuse or relay for the valve circuit
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased exhaust emissions
- Possible DEF system warning messages
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Visually inspect the wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the valve's resistance with a multimeter and compare to specifications.
Step 4: Check for power and ground at the valve connector with the ignition on.
Step 5: If wiring and valve are okay, test the PCM/ECM output signal.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can lead to increased emissions and potential damage to the SCR system. The vehicle may enter limp mode, reducing performance.
How much does it cost to fix?▼
The cost to fix P20A6 typically ranges from $150 to $400, including parts and labor. The valve itself costs $50-$150, and labor adds $100-$250 depending on the shop.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.