What it means
Negative contactor A in the battery charging system is detected as remaining closed when it should open. This can prevent the high-voltage charging path from being isolated as commanded.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Negative contactor A switches part of the battery charging system's high-voltage path. P0D0F sets when the control module detects that this contactor remains closed after it has commanded the contactor to open, so the path may not isolate as intended.
Common causes
Most likely first.
- Contacts welded closed
- Driver stuck on
- Carbon or debris buildup preventing free movement
Symptoms
- Charging system warning light may come on
- Vehicle may not enter or leave a ready-to-drive state
- Charging may be unavailable
How to diagnose it
- Read freeze-frame data and related high-voltage codes to confirm when the module commanded negative contactor A to open.
- Check scan-tool status for the commanded and reported state of negative contactor A, comparing them during a safe shutdown or charge-stop event.
- Inspect accessible connector and wiring for damage or a short that could keep the contactor driver energised.
- Have the contactor's switching state checked using the manufacturer's high-voltage isolation procedure; do not open or probe high-voltage components.
- If the contactor is mechanically stuck, distinguish welded contacts or debris from a driver circuit that is still commanding it on.
Common fixes
- Repair a wiring short that is holding the negative contactor A driver on.
- Restore a loose or damaged low-voltage connector or terminal serving the contactor control circuit.
- Replace negative contactor A if its contacts are welded or its mechanism cannot release.
- Repair the contactor driver or control module only after confirming it continues to command the contactor on incorrectly.
Can I keep driving?
Do not attempt to force the vehicle into or out of ready mode or work on the high-voltage system; the charging path may not isolate when commanded. If the vehicle will not shut down or enter its normal state, stop using it and arrange qualified high-voltage service.
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.