Powertrain, generic · Hybrid propulsion

P0CF5 Control Pilot Circuit Low

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Circuit Low means the pilot level sits under the lowest value any regular charging state can produce, as happens when the pilot wire is shorted to ground or to the protective earth contact. GM checks it in the Chevrolet Volt VICM/HPC2 tables from 2012 to 2019: with the cord unplugged, the controller feeds its own test signal through the internal diagnostic switch, and the ratio of pilot voltage to 12 V battery voltage must not fall below 0.03. 30 failures within 50 samples at 100 ms set the code as Type A, so the MIL lights after a single trip. A missing signal is P0CF3, an excessive level P0CF6, an implausible one P0CF4. While the line is pulled down, the vehicle cannot show the station that it is connected and ready, so charging does not begin.

Likely causes

Pilot wire chafed through and touching ground or the protective earth conductor
Water or corrosion bridging pilot and earth pins in the charge inlet
Failed pilot input or test circuit in the charging control module

Symptoms

  • Malfunction indicator lamp on (GM Type A)
  • Station does not detect the vehicle, charging never starts
  • Charge status indicator shows a fault after plugging in

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

control pilot circuitcharge portwiring harnesson board charger

Related codes

P0CF3P0CF4P0CF6P0CF7

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, en.wikipedia.org.