Reductant Purge Control Valve Circuit/Open
The P20A0 code indicates a problem in the electrical circuit of the reductant purge control valve, which is part of the Selective Catalytic Reduction (SCR) system used to reduce NOx emissions. The valve controls the flow of diesel exhaust fluid (DEF) into the exhaust stream. An open circuit means there is a break in the wiring or a faulty valve, preventing proper operation. This can lead to increased emissions and potential derate of engine power.
1. Most Common Causes
- Faulty reductant purge valve (DEF) with an open internal coil
- Open, cut, or corroded wiring in the valve control or power circuit
- Valve connector disconnected, loose, or with damaged/corroded terminals
- Blown fuse in the valve power supply circuit
- Internal PCM failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or derate mode
- Increased diesel exhaust fluid consumption
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P20A0 and check for related codes.
Step 2: Visually inspect the reductant purge control valve and its wiring harness for damage, corrosion, or loose connections.
Step 3: Test the valve's resistance with a multimeter; compare to manufacturer specifications (typically 10-30 ohms).
Step 4: Check for voltage at the valve connector with the ignition on; should be battery voltage (12V) on one pin.
Step 5: If wiring and voltage are okay, replace the reductant purge control valve.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally not recommended to drive long distances, as the vehicle may enter a derate mode reducing power, and emissions will be higher. Short trips to a repair shop are usually okay.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the vehicle and shop rates. The valve itself is often around $30-$80.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.