What it means
The negative contactor B of the battery charging system reports a control circuit/open 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 B is a high-voltage switch, and its control circuit carries the command that operates it. The hybrid control module sets this code when it detects an open in that circuit, so it cannot reliably command the contactor.
Common causes
Most likely first.
- Open in coil control wire
- Open contactor coil
- Pin pushed back out of connector body
Symptoms
- Hybrid-system warning light or message
- Vehicle may not enter READY mode
- Charging may be unavailable
How to diagnose it
- Record freeze-frame data and check live data for the command and reported state of negative contactor B to confirm the fault conditions.
- Inspect the accessible low-voltage harness and connector for B for a disconnected plug, damaged wire, or a terminal pushed back into the connector body.
- Use the vehicle's supported scan-tool output test to command B and observe whether the module detects a response.
- Following the manufacturer's safe procedure, test continuity of the B coil control wiring and coil, comparing results with the manufacturer's specification.
- Repair the open found, clear the code, and confirm B responds to commands and the vehicle can enter READY.
Common fixes
- Reseat a loose connector at negative contactor B.
- Repair the open or damaged section of its control wire.
- Restore a pushed-back or damaged connector terminal.
- Replace the contactor if its coil is confirmed open.
Can I keep driving?
Charging may be unavailable and the vehicle may not enter READY, so do not count on it for a trip until the fault is checked. Keep clear of high-voltage components.
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.