What it means
The drive motor A phase U-V-W output reports a circuit/open condition. Motor cannot operate reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Drive Motor A uses three phase connections, identified as U, V, and W, to produce rotation under inverter control. P0C05 sets when the module detects an open condition in the Drive Motor A phase output path, such as a broken phase wire, open winding, or terminal that has backed out of its connector.
Common causes
Most likely first.
- Open phase wire
- Open motor winding
- Pin pushed back out of connector body
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Read freeze-frame and live hybrid data for Drive Motor A phase or current faults, torque request, and motor speed to see how the open condition affects operation.
- Check for companion Drive Motor A inverter or phase codes that identify whether the fault is limited to the open condition.
- With the high-voltage system safely disabled as specified by the manufacturer, inspect Drive Motor A's U, V, and W connectors for loose, recessed, damaged, or corroded pins.
- Have a qualified technician test continuity through the three phase paths and motor windings using the manufacturer's isolation procedure.
- If the wiring and windings pass, test the inverter phase output according to the manufacturer's diagnostic procedure.
Common fixes
- Reseat or repair a backed-out phase connector terminal.
- Repair an open in the Drive Motor A phase harness.
- Replace or repair the motor if an open winding is confirmed.
- Repair or replace the inverter if its phase output is confirmed faulty.
Can I keep driving?
Avoid driving if Drive Motor A power is reduced, unpredictable, or accompanied by a hybrid-system warning; an open phase can lead to further torque loss or shutdown. Arrange safe inspection before relying on the vehicle for a long trip.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.