Powertrain, generic (extended)

P2C66 Hybrid/EV Electronics Coolant Pump A Underspeed

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2C66 reports that pump A of the electronics cooling loop, which carries heat away from inverter, DC/DC converter and often the on-board charger or drive motor, turns slower than requested. Pumps of this kind report their actual speed, and the controller compares it with the target. No manufacturer publicly documents P2C66. Ford's 2024 summary uses the same fault type, under-speed (B2), for engine coolant pump A, monitored continuously over 5 seconds above 11 V. GM's 2016 Volt judges pump A of its power electronics loop differently, as P0CEA, when coolant and charger temperatures drift apart. Worn bearings, sludge or debris, low supply voltage and partial air are typical. Expect reduced drive power or slower charging. Overspeed is P2C67, a stalled pump P2C68.

Likely causes

Worn bearings or a sluggish impeller
Debris or sludge in the pump or a restricted loop
Low supply voltage from fuse, relay or ground faults
Air pockets after a coolant service

Symptoms

  • Hybrid/EV system warning and check engine light
  • Reduced drive power or slower charging
  • Electronics temperature rises faster than usual

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,000
Time1–4 h

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

Parts involved

hybrid electronics coolant pump apower electronics coolant loop

Related codes

P2C67P2C68P0CEAP0CE9P2E47U063D

References: law.cornell.edu, fordservicecontent.com, gsi.ext.gm.com.