P0CE1: Hybrid/EV Battery Pack Coolant Control Valve A Stuck On
What to do
In cold weather this one is worth attending to promptly, because a valve stuck open can stop the battery ever warming up — which shows as reduced power, weak regenerative braking and refused rapid charging, none of which look like a cooling fault. In summer you may not notice it at all.
What this code means
The battery pack's coolant control valve has stuck in its on position.
The mirror of P0CE0, and often the less obvious of the two. A valve stuck open keeps a path connected that should sometimes be closed — which in summer may be harmless and in winter is not.
Cold is the case worth naming, because it inverts what people expect from a cooling fault. A traction battery works badly when cold and the car deliberately warms it, so a valve that will not close can pour the pack's heat into a circuit that is shedding it. The result is a pack that never reaches its working temperature: reduced power, poor regenerative braking and rapid charging refused, on a car with nothing obviously wrong. In a warm climate the same fault may never be noticed at all.
Likely causes
Start here
- Faulty battery pack coolant control valve · moderate
- Corroded or loose connector · easy
Less common
- Low coolant level · easy
- Debris or corrosion seizing the valve · moderate
- Damaged wiring harness · 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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