Powertrain, generic · Hybrid propulsion

P0C4D Hybrid/EV Battery Pack Coolant Pump A Supply Voltage Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C4D is the counterpart to P0C4C: the voltage measured on the supply of battery coolant pump A is higher than the controller allows. That can come from a feed wire shorted to another, more highly loaded circuit, from a relay that stays closed when the pump should be off, or from an overall excessive on-board voltage, for example a faulty DC/DC converter. No manufacturer documents P0C4D publicly. Ford's bulletins for the 2020 Escape, Explorer and Aviator hybrids name the sibling P0C4B for the open supply, and Bentley describes the feed of the same pump with fuse and relay for 2025–2026 hybrids. CARB requires the electrical components of battery thermal management to be monitored. If several modules log overvoltage at once, the 12 V supply is the more likely culprit than the pump circuit.

Likely causes

Supply wire shorted to another voltage-carrying circuit
Pump relay sticking closed
Excessive 12 V system voltage from a faulty DC/DC converter

Symptoms

  • MIL or hybrid or EV warning
  • Coolant pump running although the system is switched off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€20–600
Time0.3–2.5 h

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

Parts involved

hv battery pack coolant pump awiring harnessbms

Related codes

P0C4BP0C4CP0C47P0C49

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.