Reductant Pump A Control Circuit/Open
The control line driving DEF pump A is open — no continuity through the motor or harness, dosing pressure cannot be built.
Affected components
- Reductant pump
- Reductant pump relay
- Reductant supply harness
Common causes
- High likelihood: Pump motor winding open
- Medium likelihood: Open wire to pump
- Low likelihood: Pin pushed back out of connector body
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.