P0C4A: Hybrid/EV Battery Pack Coolant Pump A Control Performance
What to do
Check for air in the electronics or battery coolant circuit first, especially after any recent coolant work — a pump that spins while moving nothing produces exactly this, and bleeding it costs nothing. Otherwise expect the car to limit charging rate and power to protect the battery, which is the system working.
What this code means
The pack coolant pump is being commanded correctly and is not doing what was asked of it.
This is the outcome variant, and it is the one that catches a pump on its way out rather than one that has failed outright — worn bearings, a partly blocked circuit, or an impeller no longer moving what it should. It also catches the case the circuit codes cannot see at all: a pump that spins perfectly and moves no coolant, because the circuit it sits in has an airlock in it. Air after a coolant repair is the commonest single cause and needs a proper bleed rather than a part.
Likely causes
Start here
- Faulty electric coolant pump · moderate
- Corroded or loose connector · easy
- Air trapped in the inverter cooling circuit · moderate
Less common
- Low coolant level · easy
- Open circuit in pump wiring · 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
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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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