P261FCoolant Pump A Control Circuit Stuck On
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P261F means electric coolant pump A reports activity while the module has it switched off. GM's 2025 ECM table 25OBDG04B describes the test: with the pump commanded off or below 299 rpm for 2 s and more than 11 V on board, a feedback speed of 3,100 rpm or more for 8 of 10 seconds sets the code as Type B; the warning lamp follows on the second faulty trip. Bulletin 22-NA-077 shows how that can fail without a defect: on 2021-2022 Blazer, Acadia, XT5 and XT6 with the 3.6 L LGX, high engine speed pushes so much coolant through the auxiliary pump that its impeller free-spins above the limit; GM reflashes the ECM and warns against replacing the pump. Mercedes lists P261F71 on the OM651 Sprinter with vacuum leaks or a damaged water pump. P261E is pump B.
- What you may notice
- Check engine lamp after two faulty trips
- Usually no noticeable driveability change
- Slower warm-up when the pump really keeps running
- Likely causes
- LikelyImpeller driven by main pump flow at high rpm, fixed by ECM software (GM)
- PossibleVacuum leak or contaminated switching valve of a switchable pump (Mercedes OM651)
- RarePump electronics reporting wrong speed or not switching off
- 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: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.