P0C79Drive Motor A Inverter Voltage Too High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0C79 reports that the DC voltage at the inverter of drive motor A rose above its protection limit. Overvoltage can come from regenerative energy the battery cannot absorb, from a contactor opening under load or a loose high-voltage connection, and it can also be a false reading. In the 2018 Outlander PHEV a hardware comparator in the front motor control unit trips at 370 V; one event with the IGBTs active, or 0.5 s with them shut down, sets the code; after ruling out other voltage codes, the manual checks the torque of the battery cable at the power drive unit. Subaru revised its diagnosis for the 2014-2015 Crosstrek Hybrid (16-114-18), and Audi traces intermittent P0C7900 on the Q4 e-tron to software. Drive motor B uses P0C7A, the generator P0C7B.
- What you may notice
- Hybrid or EV warning lamp, electrical system fault message
- Drive system will not activate or shuts down until restarted
- Reduced drive power
- Likely causes
- PossibleBattery cable at the inverter loose or not at specified torque
- PossibleInverter or its voltage detection faulty
- PossibleVoltage spike from regeneration or a contactor opening under load
- RareMotor control software, fixed by an update
- 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: €100 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.