Reductant Injection Valve Stuck Open Bank 1 Unit 1
The P20F6 code indicates that the reductant injection valve (part of the Selective Catalytic Reduction system) for Bank 1 Unit 1 is stuck open. This valve controls the flow of diesel exhaust fluid (DEF) into the exhaust stream. When stuck open, DEF is continuously injected, which can lead to over-dosing, crystallization, and potential damage to the SCR catalyst. The issue is often caused by a faulty valve, electrical problems, or contamination in the DEF system.
01. Most Common Causes
- Faulty reductant injection valve
- Electrical short or open in valve circuit
- Contaminated or crystallized DEF blocking valve
- Damaged wiring or connector
02. Symptoms You Will Notice
- Check Engine Light on
- Reduced engine performance or limp mode
- Excessive DEF consumption
- Possible white smoke from exhaust
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P20F6 is present.
Step 2: Inspect the reductant injection valve and wiring for damage or corrosion.
Step 3: Test valve resistance and compare to specifications (typically 2-5 ohms).
Step 4: Check for DEF crystallization around the valve and clean if necessary.
Step 5: If valve is faulty, replace it and clear codes.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can damage the SCR system and cause further issues. You may experience reduced performance or limp mode.
How much does it cost to fix?▼
The cost typically ranges from $200 to $600, including parts and labor. The valve itself costs $100-$300, and labor is about $100-$300.