Reductant Quality Sensor Circuit Range/Performance
DEF quality sensor reads in range but reports an off-spec urea concentration — typically diluted DEF or non-DEF fluid in the tank.
Affected components
- Reductant quality sensor
Common causes
- High likelihood: DEF diluted with water
- Medium likelihood: Wrong fluid in DEF tank
- Low likelihood: Sensor element aged beyond calibration window
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.