P05EFReductant Pump Supply Voltage Circuit Low
- 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. P05EF means the supply voltage is too low or the supply line is shorted to ground. GM's 6.6 L diesel monitors the same high-side driver under P1043 (short to ground with driver on, about 0.5 Ω, 3 s, first trip); Ford flags its pump controller voltage below 8.5 V. No manufacturer document available to us uses this exact code; GM and Ford monitor the same function under their own codes. 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
- Likely causes
- LikelySupply line shorted to ground (chafed against the frame)
- PossibleHigh contact resistance or corrosion in the connector
- PossiblePump shorted internally or stiff (high current)
- RareWeak battery or charging system
- 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.