What it means
The negative contactor C of the battery charging system reports a control circuit low 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 switches part of the high-voltage battery charging path. The control module monitors the voltage in its control circuit and sets this code when that signal is lower than expected. A control wire short to ground, a shorted coil, or corroded connector pins can pull the circuit low.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in contactor coil
- Connector pins corroded - high contact resistance
Symptoms
- Hybrid or EV system warning
- Charging may be disabled
- Vehicle may not start or enter Ready mode
How to diagnose it
- Save freeze-frame data and check related hybrid or EV codes, then use live data to confirm the negative contactor C circuit is being reported low.
- With the vehicle powered down as specified by the manufacturer, inspect contactor C wiring for damage or contact with ground and check its connector for corrosion or moisture.
- Inspect the connector terminals for pushed-back pins, poor fit, or contamination that could interfere with the control signal.
- Following the manufacturer's high-voltage safety and isolation procedures, test the control wire for a short to ground and check coil condition against the manufacturer's specification.
- If the wire and coil pass, follow the manufacturer's circuit tests to check the contactor driver and module input.
Common fixes
- Clean or repair corroded terminals at negative contactor C.
- Repair a control wire shorted to ground or damaged harness section.
- Replace negative contactor C if its coil is internally shorted or outside the manufacturer's specification.
- Repair the control driver or module if circuit testing confirms it is pulling the signal low.
Can I keep driving?
Do not depend on the vehicle for travel if it will not enter Ready mode, and do not keep retrying charging when it is disabled. The high-voltage path may remain unavailable, leaving the vehicle unable to start or charge.
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.