P05F1Reductant Pump Supply Voltage Circuit Stuck On
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- The electric supply pump in the diesel exhaust fluid (DEF, AdBlue) tank module builds the dosing pressure for the SCR catalyst. Its supply voltage is monitored separately from the pump control circuit (P208A ff); CARB requires SCR components and their outputs to be checked for circuit faults and function. P05F1 means the pump supply stays on although the module switches it off – typically detected after the switch-off command, e.g. during after-run, when the feedback still shows voltage. A welded relay or a shorted semiconductor switch is the usual reason. Chrysler (FCA) lists this code among those that trigger the DEF inducement: a 'Service DEF System' warning, a countdown after 50 miles and no restart after 150 miles (P241D). Without supply the pump cannot build pressure, dosing stops and NOx rises; pressure or SCR efficiency codes may follow.
- What you may notice
- Check engine light on
- DEF/AdBlue warning, possibly countdown to no-restart
- Follow-up codes for low DEF pressure or SCR efficiency
- Pump keeps running after switch-off, battery drains
- Likely causes
- LikelyPump supply relay stuck (welded contacts)
- PossibleSemiconductor driver shorted
- PossibleExternal voltage or short to positive in the harness
- RareSoftware or calibration fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.