Reductant Heater A Control Circuit/Open
Reductant heater A (typically the supply line heater nearest the tank) control circuit is open — that segment of DEF line will not be kept above freezing in winter.
Affected components
- Reductant line heater a
Common causes
- High likelihood: Heater winding open
- Low likelihood: Pin pushed back out of connector body
- Low likelihood: Cracked solder joint inside the module or sensor
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
Related codes
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.