Reductant Pump A Control Performance/Stuck Off
DEF pump A receives a run command but does not start, or shuts off prematurely — pump performance is below threshold.
Affected components
- Reductant pump
Common causes
- High likelihood: Pump motor seized — DEF crystallised inside pump head
- Medium likelihood: Motor brushes worn
- Low likelihood: Carbon or debris buildup preventing free movement
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.