What it means
The control module detects a fault in the hybrid/EV battery negative contactor circuit.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The negative contactor is a high-voltage switch that connects the battery’s negative side to the vehicle’s drive system. The control module monitors its circuit and switching response; this general circuit code indicates an abnormality but does not by itself identify a stuck-open condition.
Common causes
Most likely first.
- Contactor circuit wiring or connector fault
- Contactor or coil fault
- Control circuit fault
Symptoms
- Hybrid system warning light
How to diagnose it
- Read all hybrid-system codes and freeze-frame data to determine whether the negative-contactor fault appears with battery, interlock, or positive-contactor codes.
- Check whether the vehicle reaches ready mode and note whether electric drive is limited or unavailable.
- With the vehicle safely powered down as specified by the manufacturer, visually inspect the negative contactor's accessible wiring and connectors for looseness, corrosion, damage, or overheating.
- Use scan-tool data to compare the commanded negative contactor state with the reported state during the prescribed diagnostic check.
- Have a qualified hybrid technician test the negative contactor coil and control wiring against the manufacturer's specification; do not probe high-voltage terminals.
- If the circuit checks pass, follow the manufacturer's procedure to assess the negative contactor and control-module feedback.
Common fixes
- Clean and secure a loose or corroded negative-contactor connector.
- Repair damaged wiring in the negative contactor circuit.
- Replace the negative contactor if its coil or switching response fails the manufacturer's tests.
- Repair or replace the control module only if its circuit output or feedback fails the specified checks.
Can I keep driving?
If hybrid operation is limited or the vehicle will not enter ready mode, avoid driving it and arrange qualified hybrid diagnosis. The negative contactor is part of the high-voltage battery connection, so do not handle its wiring yourself.
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.