What it means
The negative contactor C of the battery charging system reports a stuck closed condition. HV charging path cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Negative contactor C is a high-voltage switch on the return side of the battery charging path. The module checks whether it opens when commanded; this code sets when it continues conducting or feedback indicates closed after an open command.
Common causes
Most likely first.
- Contactor contacts welded closed
- Output driver stuck on
- Carbon or debris buildup preventing free movement
Symptoms
- Hybrid or EV system warning
- Charging may be disabled
- Vehicle may not start or enter Ready mode
How to diagnose it
- Read freeze-frame data and related codes to see when negative contactor C was commanded open and what feedback the module recorded.
- Check warning messages and charging or Ready status to establish whether the fault occurs during charging shutdown or vehicle start-up.
- With the vehicle powered down under the manufacturer's high-voltage safety procedure, have a qualified technician inspect negative contactor C's connector and accessible wiring for overheating or damage.
- Use scan-tool command and feedback data, if available, to compare negative contactor C's commanded state with its reported state.
- Have a qualified technician test whether negative contactor C still conducts when commanded open and distinguish welded contacts from a driver or feedback fault using the manufacturer's procedure.
Common fixes
- Repair damaged or corroded negative contactor C connector or control wiring.
- Repair the contactor driver circuit if testing shows its output is stuck on.
- Replace negative contactor C if its contacts are welded or it cannot open as commanded.
Can I keep driving?
Charging may be disabled, and the vehicle may fail to enter Ready mode or start. Avoid relying on the vehicle until the fault is diagnosed; high-voltage contactor work should be handled by a qualified technician.
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.