What it means
The control circuit B for the hybrid battery precharge contactor reports a low condition. Pre-charging the DC link before main contactor closure 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
The hybrid or EV battery precharge contactor B control circuit operates the coil that helps safely bring the inverter's DC link voltage up before the main battery contactors close. The control module monitors circuit B for an electrical level below its expected range. If it detects that low condition, it may be unable to command precharge reliably and can restrict hybrid or electric operation.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in contactor coil
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Use a scan tool to record freeze-frame data and check hybrid battery and contactor codes before clearing anything, since related faults may explain when circuit B went low.
- With the vehicle powered down according to the manufacturer's safety procedure, inspect the precharge contactor B connector and harness for chafing, corrosion, pin damage, or a wire touching ground.
- Check whether the code returns after clearing it and following the manufacturer's enable conditions; an intermittent return may point to a connection or harness fault.
- With the high-voltage system made safe as specified by the manufacturer, test circuit B for an unintended short to ground and check its continuity and connections.
- If the wiring passes, test the precharge contactor B coil and control circuit using the manufacturer's procedure to distinguish an internally shorted coil from a wiring fault.
Common fixes
- Repair damaged insulation or a control wire shorted to ground in circuit B.
- Clean, secure, or repair a corroded or damaged precharge contactor B connector.
- Replace the precharge contactor if its coil is internally shorted.
- Clear the code and confirm the precharge system operates correctly after repair.
Can I keep driving?
Avoid relying on electric drive or attempting repeated restarts or charging if power is limited or the hybrid system warning is active; the vehicle may enter limp mode or fail to start. Have it checked promptly, and do not handle high-voltage components unless qualified.
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.