Reductant Heater Coolant Control Valve Performance
The P20B2 code indicates that the Engine Control Module (ECM) has detected a performance issue with the reductant heater coolant control valve. This valve regulates coolant flow to the reductant heater, which warms the diesel exhaust fluid (DEF) in cold temperatures to prevent freezing. When the valve fails to operate correctly, the DEF may not be heated properly, leading to reduced NOx conversion efficiency and potential emissions system issues.
01. Most Common Causes
- Faulty reductant heater coolant control valve
- Wiring or connector issues in the valve circuit
- Low coolant level or air in the cooling system
- ECM software or calibration problem
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Increased emissions
- Possible DEF system warnings
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect the valve and its wiring for damage or corrosion.
Step 3: Test the valve's resistance and operation using a multimeter and scan tool.
Step 4: Check coolant level and bleed air from the cooling system if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive short distances, but prolonged driving may cause increased emissions and potential damage to the DEF system. It is recommended to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the valve price and labor rates.