P0EF3

Code

Generic P — Powertrain

Drive Motor C Temperature Sensor Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 29 RU: 27

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Page language: EN

Causes

Short to ground in the sensor signal or harness
Open or shorted sensor (thermistor) inside the drive motor
Corroded, loose or damaged connector/pins at sensor or controller
Faulty or missing reference voltage or ground from the motor controller/VCU
Water intrusion or contamination at sensor or connector
Faulty motor controller/VCU input circuit

Symptoms

Malfunction Indicator Lamp (MIL) or EV/HEV warning lamp illuminated
Drive motor C temperature reading abnormally low or fixed at an extreme value in scan tool
Reduced motor output or limp/limited drive mode
Regeneration or charging behavior reduced/disabled
Service messages related to motor temperature or propulsion system

What to check

Scan tool: read freeze frame, pending/confirmed status and live data for motor C temperature
Visual inspection of sensor connector, pins and wiring for damage, corrosion, or water
Wiggle test wiring while monitoring live data to find intermittent shorts/open circuits
Measure sensor signal voltage with ignition ON (key ON, vehicle in service mode) and compare to expected range
Measure sensor resistance at known ambient temperature (if accessible) and compare to specification or reference table
Check for continuity to ground or short to chassis on the signal wire (with power removed)

Signal parameters

Sensor type: typically an NTC thermistor inside the drive motor (resistance changes with temperature)
Signal voltage: normally a varying voltage within the controller input range (commonly ~0.5–4.5 V depending on temp and system design); a very low voltage (< ~0.5 V) usually indicates a short to ground or very low resistance
Resistance behavior: NTC thermistor shows higher resistance at low temperature and lower resistance at high temperature (exact kΩ values are manufacturer specific)
Controller input: expects a plausible range and plausibility compared to other motor/pack temperatures

Diagnostic algorithm

Retrieve DTC details and live data with a scan tool. Note freeze-frame and when fault occurs (cold/hot/startup/driving).
Observe the reported motor C temperature value while performing key ON and engine off/drive cycles to confirm low reading and any correlation to vehicle actions.
Perform a visual inspection of the drive motor C harness, connector and surrounding area for damage, corrosion, pin push-out or water entry. Repair obvious damage.
With the vehicle powered down and following proper high-voltage safety/isolation procedures, disconnect the motor C temperature sensor connector and inspect terminals. Clean or repair as needed.
Measure sensor resistance at the sensor harness (or motor connector) at ambient temperature and compare to manufacturer curve/spec. If inaccessible inside the motor, measure continuity and check for short to ground.
Backprobe the sensor signal wire at the controller connector (or harness) with key ON and record signal voltage. Check reference voltage and ground present at the controller connector.
Check for short to ground between signal wire and chassis with power removed. Also check for short to battery/ignition supply if applicable.
If wiring and connectors are good but readings remain out of range, replace the motor temperature sensor (or repair motor harness). If fault persists after sensor replacement, suspect controller/VCU input circuit and test/replace per manufacturer procedures.
Clear codes, perform operational test and a road test or appropriate functional test while monitoring live data to confirm repair.
Safety note: Drive motor work may involve high-voltage components. Follow manufacturer high-voltage isolation and lockout procedures and use trained personnel and PPE.

Likely causes

Wiring shorted to ground between sensor and controller
Failed temperature sensor element in drive motor C
Corroded/loose connector at the motor or controller
Controller-side input fault (less common)

Fault status

⚠️ Status

Drive Motor C temperature sensor circuit is reporting a low signal (low voltage/low resistance or short to ground). The motor temperature input is out of expected range and the propulsion system may limit operation until the issue is resolved.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0-4.0 hours