P0C0B: Drive Motor A Inverter Power Supply Circuit/Open
What to do
If the car will not drive electrically and there are no phase codes stored, this is the more likely half and the cheaper one — a high-voltage fuse, a contactor or a bolted joint rather than a motor. Ask which side is actually being quoted. Nothing here is approachable without high-voltage training and equipment.
What this code means
The high-voltage supply feeding drive motor A's inverter is missing or open.
This is the DC side, and separating it from the AC side is what makes the whole group diagnosable. An inverter has two electrical faces: direct current in from the traction pack, and three-phase alternating current out to the motor. The phase codes at P0C05 are the output. This is the input — the busbars, the high-voltage fuse and the main contactors between pack and inverter.
The consequences differ completely. A phase fault leaves an inverter that is powered and running badly; a supply fault leaves an inverter that is not there at all. No hum, no torque, no attempt.
Which gives a clean discriminator that costs nothing: a vehicle with no drive and no phase codes points at the supply, not the motor. And the supply side is the friendlier half — contactors, a fuse and bolted joints are inspectable and individually replaceable, where the motor is neither.
Likely causes
Start here
- Corroded or loose connector · specialist
- Faulty battery contactor · specialist
Less common
- Damaged high voltage cable insulation · specialist
- Faulty power inverter · specialist
Rare
- Welded battery contactor · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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