Reductant Purge Control Valve Circuit High
The P20A3 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the reductant purge control valve circuit. This valve is part of the selective catalytic reduction (SCR) system, which injects diesel exhaust fluid (DEF) into the exhaust stream to reduce NOx emissions. A high voltage signal suggests a short to power, open circuit, or a faulty valve, potentially preventing proper DEF purge and leading to emissions non-compliance.
1. Most Common Causes
- Faulty reductant purge control valve
- Short to power in the valve circuit
- Open or damaged wiring/connectors
- Corroded or loose electrical connections
- Failed PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased diesel exhaust fluid consumption
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the reductant purge control valve and its wiring for damage, corrosion, or loose connections.
Step 3: Test the valve's resistance with a multimeter; compare to manufacturer specs (typically 10-30 ohms).
Step 4: Check for voltage at the valve connector with the ignition on; should be battery voltage on one pin and ground on the other. If voltage is high or absent, trace the circuit for shorts or opens.
Step 5: If wiring and valve test OK, suspect a PCM fault; perform a PCM reset or reprogramming if necessary.
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 reduced engine performance, increased emissions, and potential damage to the SCR system. However, you may be able to drive short distances to a repair shop.
How much does it cost to fix?▼
The cost to fix P20A3 typically ranges from $50 to $150 for diagnosis and simple repairs like cleaning connections or replacing a valve. If the PCM needs replacement, costs can exceed $500.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.