Powertrain, generic (extended)

P261F Coolant Pump A Control Circuit Stuck On

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Impeller driven by main pump flow at high rpm, fixed by ECM software (GM)
Vacuum leak or contaminated switching valve of a switchable pump (Mercedes OM651)
Pump electronics reporting wrong speed or not switching off

Symptoms

  • Check engine lamp after two faulty trips
  • Usually no noticeable driveability change
  • Slower warm-up when the pump really keeps running

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–900
Time0.3–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

coolant pump acontrol modulewiring harness

Related codes

P261EP2600P2601P2602P2603

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.