Powertrain, generic

P0EF4 Drive Motor C Temperature Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0EF4 reports a drive motor C temperature signal above the plausible window. For an NTC sensor on a pull-up this equals an impossibly cold winding, the picture produced by an open sensor, a broken wire, an unplugged connector or a short to the reference voltage. No manufacturer documents P0EF4 publicly. GM's ELR motor controller treats the same situation for motor B as P0A33 once the value reads below −41 °C, near 5 V, while Ford flags the coil sensor of its 2019 hybrids once the voltage exceeds 4.8 V for 32 ms. A sensor that claims far too low a temperature would hide real overheating, so the controller switches to a substitute value and limits the output of motor C. Check the connector at the motor first; the low-side sibling is P0EF3.

Likely causes

Sensor connector unplugged, loose or with pushed-back pin
Broken signal or ground wire of the sensor
Thermistor open internally
Signal wire shorted to the 5 V reference

Symptoms

  • Reduced power of motor C
  • Motor temperature stuck at the lowest value in the live data
  • Warning lamp on

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–2,500
Time0.5–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

drive motor c temp sensorwiring harnesshybrid control module

Related codes

P0EF3P0EF1P0EF2P0EF5P0A33P0A2D

References: gsi.ext.gm.com, fordservicecontent.com, law.cornell.edu.