P0A78 code meaning
Drive Motor A Inverter Performance
Powertrain system Generic code P0Axx codes Check engine light
What P0A78 means
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.
P0A78 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0A78
- MIL and hybrid or high-voltage warning
- No electric drive, engine-only operation
- Stop safely warning on some models
Common causes of P0A78
- Most likelyIGBT desaturation or short in the inverter power stage
- Most likelyPower inverter module defective (replaced on Jeep Wrangler 4xe)
- PossibleHybrid control software requiring update
- Less likelyShorted winding or phase cable of drive motor A
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
InverterDrive motor a
What each part of P0A78 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| 78 | The exact fault in that area. |
What to do next
- Note P0A78 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0A78
What does P0A78 mean?
P0A78 means "Drive Motor A Inverter Performance". P0A78 means the inverter stage feeding drive motor A has reported a power-switch fault. It is a generic code, so it means the same on every make.
Is it safe to drive with P0A78?
Drive gently and only to a workshop. With P0A78 the car can go into limp mode (reduced power) to protect itself.
Will P0A78 fail an emissions test?
Yes, it can. P0A78 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0A78 to fix?
Difficulty: workshop only. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0A78 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.