Reductant Metering Unit Heater Control Circuit Performance
Metering unit heater is electrically OK but does not warm the block within the expected time — partial winding fault or excessive heat loss.
Affected components
- Reductant metering unit heater
Common causes
- High likelihood: Partial winding fault
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.