Reductant Quality Sensor Circuit Intermittent/Erratic
The reductant (DEF/AdBlue) quality sensor signal drops out or jumps intermittently. Loose connector, dilution noise, or ground reference offset.
Affected components
- Reductant quality sensor
- Wiring harness
- Scr module
Common causes
- High likelihood: Sensor connector not seated
- Medium likelihood: Noisy ground reference
- Low likelihood: Connector with intermittent contact under vibration
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
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
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.