P0CEE
Hybrid/EV Electronics Coolant Temperature Sensor A Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- C
- AreaHybrid propulsion
- EE
- FaultThe specific fault in that area
What it means
P0CEE is the generic code for a fault in the circuit of coolant temperature sensor A in the hybrid or EV electronics cooling system, which cools parts such as the inverter, DC-DC converter or onboard charger. The control unit set it because the sensor signal was outside the expected range, either too high or too low, or was implausible compared with other temperature data. Which components sit on this loop, and which sensor is 'A', depends on the model.
Symptoms
- Warning light on, such as the hybrid/EV system fault or general malfunction lamp
- Reduced power or limp mode to protect the power electronics
- Reduced or restricted charging speed, or charging stopping early
- Electronics cooling pump or fan running constantly or not behaving normally
- Temperature readout on the dash or in live data stuck, missing or implausible
- Hybrid or EV system refusing to enter ready mode (in some cases)
Possible causes
- Damaged wiring, corrosion or a poor connection at the coolant temperature sensor connectorlikely
- Faulty electronics coolant temperature sensor giving an out-of-range or stuck signallikely
- Low coolant level or air in the electronics cooling loop causing a false or erratic readingpossible
- Short or open circuit in the sensor signal or ground wire, or a short to supply or earthpossible
- Cooling pump failure or blocked flow causing a genuinely abnormal temperature that the sensor correctly reportspossible
- Fault inside the control unit or power electronics unit that monitors the sensorrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, and note any other cooling, pump or temperature sensor codes.
- Check the electronics coolant level and condition when cold, following the manufacturer's procedure, and look for leaks.
- Visually inspect the sensor, its wiring and the connector for chafing, corrosion, water ingress, bent pins or heat damage.
- Compare the sensor's live reading with other temperature data, such as ambient and other coolant sensors, on a cold car; they should be similar.
- Check the cooling pump runs when commanded and that coolant is actually flowing through the loop.
- Measure sensor resistance and the reference voltage, signal and ground at the connector against the manufacturer's specification, and wiggle-test the harness while watching live data.
- Test the wiring for continuity and for shorts to earth or supply between the sensor and the control unit.
- Only trained staff should work on high-voltage components. Follow the manufacturer's isolation procedure before touching any orange cabling or power electronics.
How to fix
- Repair or replace damaged wiring and clean or replace a corroded or loose connector.
- Replace the electronics coolant temperature sensor if its readings are out of specification.
- Top up or refill the electronics cooling loop with the specified coolant and bleed air using the manufacturer's procedure, and fix any leak found.
- Replace a failed electronics cooling pump or clear a flow restriction.
- If all circuits and the sensor test good, have the control unit checked and replaced or updated per the manufacturer's guidance if a fault or known software issue is confirmed.
Can I keep driving?
The car may be driven with care for a short distance, but power may be limited and the power electronics could overheat if the cooling is genuinely faulty. Get it checked soon, and stop if a hybrid/EV system overheating warning appears.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.