Powertrain, generic · Hybrid propulsion

P0CF0 Hybrid/EV Electronics Coolant Temperature Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The signal voltage of the electronics coolant temperature sensor drops close to zero, which almost always means the signal wire touches ground or the sensor is shorted internally. Low refers to the voltage, not to the temperature. GM sets the code below 2 % of the 5 V reference (0.1 V) in the 2011 Volt, the ELR and the 2016 HPC2 table, and below 4 % (0.2 V) in the 2016 Volt and the 2019 HPC2 table. Counting is 16 of 20 samples at 250 ms or 4 s in a 5 s window, with more than 9 or 10.2 V supply, Type B, two trips. The open or high case is P0CF1, a plausible but wrong value is P0CEF. With no usable reading, the controller assumes the worst, runs the pump and can limit inverter and charging power.

Likely causes

Sensor signal wire shorted to ground
Internally shorted temperature sensor
Water in the connector bridging signal and ground

Symptoms

  • Malfunction indicator lamp or hybrid warning
  • Scan tool shows an implausibly high coolant temperature
  • Pump running constantly, power or charging reduced

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–400
Time0.5–2 h

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

Parts involved

hybrid electronics coolant temp sensor awiring harnesshybrid control module

Related codes

P0CEEP0CEFP0CF1P0CF2P2B22

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.