Powertrain, generic · Hybrid propulsion

P0C4C Hybrid/EV Battery Pack Coolant Pump A Supply Voltage Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C4C reports that the supply voltage reaching battery coolant pump A is below the expected level while the circuit is not fully open. Typical reasons are high resistance in the feed, a corroded fuse contact, a weak relay, a poor ground or a short to ground that drags the line down. No manufacturer documents P0C4C publicly. Ford uses the sibling P0C4B for the open supply circuit on its 2020 Escape, Explorer and Aviator hybrids, and Bentley's bulletin on P0C4700 for 2025–2026 Continental GT and Flying Spur hybrids shows what such a feed contains: a 10 A fuse, a relay and a harness route that can chafe at the rear suspension. CARB requires the electrical parts of battery thermal management to be monitored. A pump that receives too little voltage runs slowly or not at all.

Likely causes

High resistance from corroded fuse, relay contacts or connector
Poor pump ground connection
Supply wire chafed and shorted to ground

Symptoms

  • MIL or hybrid or EV warning
  • Coolant pump running slowly or intermittently
  • Battery power reduced when the pack warms up

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

P0C4BP0C4DP0C47P0C48P0CFF

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