P0A78Drive Motor A Inverter Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- MIL and hybrid or high-voltage warning
- No electric drive, engine-only operation
- Stop safely warning on some models
- Likely causes
- LikelyIGBT desaturation or short in the inverter power stage
- LikelyPower inverter module defective (replaced on Jeep Wrangler 4xe)
- PossibleHybrid control software requiring update
- RareShorted winding or phase cable of drive motor A
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.