Reductant Quality Module Performance
DEF quality module reports an internal performance fault — self-test failed or measurement loop unable to converge. The module may need replacement.
Affected components
- Reductant quality sensor
Common causes
- High likelihood: Internal module fault
- Low likelihood: Module software outdated, reflash may resolve
- Low likelihood: Supply voltage outside specification
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
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.