OBD-II code · Powertrain (generic)
P05EF Reductant Pump Supply Voltage Circuit Low
Same as P05EE with the supply voltage below the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P05EF?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySupply voltage low
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
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)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.8–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Pump
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.