What it means
Same as P05EE with the supply voltage above 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.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant pump supply circuit provides electrical power to the DEF/AdBlue dosing pump. The control module sets P05F0 when the voltage it detects on that supply is higher than the plausible range. This points to an over-voltage condition in the monitored circuit, not necessarily a pump that has failed.
Common causes
Most likely first.
- Supply voltage above design range
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light or emissions warning may illuminate
How to diagnose it
- Record freeze-frame data and check live pump supply voltage to confirm when the high reading occurs and whether it follows a pump command.
- Inspect the pump supply harness and connectors for a pinched wire touching battery positive or another supply, melted insulation, water, and terminal damage.
- Check vehicle charging voltage and related supply circuits to rule out a broader over-voltage condition.
- Compare voltage at the pump supply terminal with the control module's reported value, following the wiring diagram and safe probing practices.
- With the circuit isolated as specified by the manufacturer, test for a short to supply and check the relay and module output for unintended voltage.
Common fixes
- Repair a pinched or chafed supply wire that is contacting a power source.
- Clean, dry, and repair damaged pump supply connector terminals and seals.
- Replace a relay with confirmed stuck or misrouted contacts.
- Repair a confirmed module output or voltage-monitoring fault after verifying the harness.
Can I keep driving?
If the vehicle operates normally, a short trip may be possible, but have the high supply voltage checked promptly because it can disrupt or damage the pump circuit. DEF/AdBlue dosing may be affected, and an emissions warning or starting countdown may follow.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.