Powertrain, generic · Hybrid propulsion

P0C0B Drive Motor A Inverter Power Supply Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C0B flags a lost or interrupted supply inside the motor A inverter. GM reads it from the IGBT module status: when the gate drive supply falls below its threshold, the module reports a bias fault; on eAssist the 5 V rail below 3.5 to 4.3 V or the 15 V rail below 10.4 to 12.6 V counts, with run/crank above 7 V. The 2012 trucks enable it between 9.5 and 18 V; the 2016 to 2019 tables need 0.002 to 0.168 s of fault within short windows, Type A, one trip. Mercedes applies the code to the high-voltage supply of the inverter in the belt starter-alternator of P3 hybrids (subtypes 16 and 17) and replaces that unit. Expect loss of electric drive or engine start.

Likely causes

Failed gate-drive power supply inside the motor A inverter
Low 12 V feed, blown fuse or poor ground to the inverter control board
Open high-voltage feed to the inverter, e.g. in a belt starter-alternator (Mercedes LI15.40-P-077947)

Symptoms

  • Malfunction indicator lamp after one drive
  • Electric drive or motor generator unavailable
  • Engine cannot be started, only electric driving possible (Mercedes P3 hybrids)

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–5,000
Time0.5–6 h

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

Parts involved

drive motor a inverterwiring harnesshybrid control module

Related codes

P0C0CP0C0DP0C0EP0A78P0BE6P0BEAP0BEEP0D2E

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