Powertrain, generic · Hybrid propulsion

P0A78 Drive Motor A Inverter Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A78 means the inverter stage feeding drive motor A has reported a power-switch fault. GM explains the check in its hybrid OBD tables: the IGBT module watches each phase for desaturation, a sign of a short between the upper and lower switch; if that status persists for about 2 ms the code sets as Type A, MIL on the first trip. Stellantis replaced the power inverter module on 2021 Jeep Wrangler 4xe with P0A78 and P0A79, which ran on engine power only, and refreshed hybrid control software on the 2017 Pacifica Hybrid. Land Rover logs P0A78 in the inverter converter of 2024-25 Range Rover models and asks not to clear it before diagnosis. P0A79 is motor B, P0A7A the generator inverter, P0A3C overheating of inverter A. Expect a warning and loss of electric drive.

Likely causes

IGBT desaturation or short in the inverter power stage
Power inverter module defective (replaced on Jeep Wrangler 4xe)
Hybrid control software requiring update
Shorted winding or phase cable of drive motor A

Symptoms

  • MIL and hybrid or high-voltage warning
  • No electric drive, engine-only operation
  • Stop safely warning on some models

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€200–6,000
Time1–6 h

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

Parts involved

inverterdrive motor a

Related codes

P0A79P0A7AP0A3CP0A1BP0A90

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.