P0EF5: Drive Motor C Temperature Sensor Circuit Intermittent/Erratic
What to do
Expect reduced power, most noticeably when working the car hard, and possibly stability control intervening more than usual. It is drivable. If the car has a motor per wheel, the loss of power may feel larger than one motor's share — that is deliberate balancing rather than a second fault.
What this code means
The circuit for the third drive motor's temperature sensor is faulty.
A third drive motor, and what that implies is worth stating because it changes the diagnosis.
Motors A and B are the two axles on an all-wheel-drive electric car. A third means something else again — most often a per-wheel arrangement, where torque is directed individually and the car steers partly by driving one side harder than the other.
Which makes a fault in motor C felt rather than merely reported. Losing one of two axles reduces power symmetrically. Losing one of three or four wheel motors makes the car asymmetric, and the vehicle will deliberately back off the others to keep it balanced — so the loss of power is larger than the fraction suggests, and it may be accompanied by stability control intervening more than usual.
On temperature specifically, the motor derates before it stops. So the honest symptom is a car that is fine cold and progressively less willing as it is worked — and, because the compensation is automatic, a driver may notice only that it feels different rather than that anything is wrong.
Comes and goes. A motor's harness moves, heats and vibrates more than almost anything else on the car, so intermittent faults here are mechanical far more often than electrical.
Likely causes
Start here
- Faulty motor temperature sensor · specialist
- Corroded or loose connector · specialist
- Open circuit in sensor wiring · specialist
Less common
- Faulty inverter coolant pump · specialist
- Damaged wiring harness · specialist
Symptoms
Components involved
Information, not instruction
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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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