P26D4Engine Coolant Pump Supply Voltage Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P26D4 narrows the supply fault of the engine coolant pump down to too low a voltage on its power feed. There is no public manufacturer documentation for this code. CARB's OBD rule requires circuit monitoring for electrical components, and Ford shows how the supply of a smart pump is judged with the general code P26D3: there the PCM infers a dead feed from lost pump communication plus a rising coolant temperature. A low reading, unlike a complete loss, typically comes from a corroded fuse holder or connector, a partially broken wire, a relay with burnt contacts or a short to ground that pulls the line down. The pump may then still run but slowly or with interruptions, so heating and engine temperature may become unsteady; the related P26D0 compares the pump's internal electronics voltage instead.
- What you may notice
- Check engine lamp on
- Fluctuating engine temperature or heater output
- Likely causes
- LikelyCorroded fuse holder or connector in the pump feed
- PossibleSupply relay with burnt contacts
- RarePartial short to ground on the feed wire
- 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: €20 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.