Reductant Heater Coolant Control Valve Stuck Closed
The valve that routes engine coolant to heat the AdBlue lines is stuck closed - AdBlue lines do not warm up and may freeze in cold weather, blocking dosing.
Affected components
- Reductant coolant control valve
Common causes
- High likelihood: Valve stuck closed
- Low likelihood: Carbon or debris buildup preventing free movement
- Low likelihood: Component wear with age - mechanical play
Possible symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.