P0C4D: Hybrid/EV Battery Pack Coolant Pump A Supply Voltage Circuit High
What to do
As P0BBF's argument — a pump with no supply is indistinguishable from a failed pump, and the supply is a fraction of the price. Expect charging to be slower until it is fixed.
What this code means
The power supply feeding the battery pack's coolant pump is reading higher than expected, usually a measurement or wiring fault rather than a genuine overvoltage.
Supply, not command — the same distinction the fan supply makes at P0BBF, and the same practical consequence: check the fuse, relay and connector before the pump. The command side is at P0C47.
Likely causes
Start here
- Corroded or loose connector · easy
- Blown fuse or failed supply · easy
Less common
- Open circuit in pump wiring · moderate
- Faulty electric coolant pump · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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