Reductant Tank Heater Control Circuit Performance
DEF tank heater is electrically OK but does not warm the tank within the expected time — element is partially open, fluid level too low for proper heat transfer, or the heater is undersized for the ambient temperature.
Affected components
- Reductant tank heater
- Reductant temperature sensor
Common causes
- High likelihood: Heater element partially open
- Medium likelihood: DEF level too low for heat transfer
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.