Powertrain
generic / SAE
P05F1
Reductant Pump Supply Voltage Circuit Stuck On
The supply relay or driver for the reductant pump is welded or stuck active - the pump runs continuously, even with the engine off, draining the battery and over-pressurising the dosing circuit.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number5 / F1
Possible causes
- Supply relay welded high
- Carbon or debris buildup preventing free movement low
- Component wear with age - mechanical play low
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)
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 120–500 €
- Estimated time: 0.6–2 h
- Component: reductant pump supply relay
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012