What it means
The ECM detects a high fault on the battery charger coupler temperature sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery charger coupler temperature sensor B measures coupler temperature so the vehicle can manage charging safely. The control module sets this code when sensor B’s signal is higher than expected, which may result from a signal wire short to battery voltage, an open sensor, or a poor connector connection.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Scan for related charging codes and save freeze-frame data, including sensor B’s reported temperature and charge status.
- With charging stopped, inspect sensor B’s connector and wiring for damage, corrosion, loose pins, or contact with a power feed.
- Compare the reported sensor B temperature with ambient conditions and other available temperature readings to identify an implausibly high value.
- Using the wiring diagram and required safety procedures, check the signal wire for a short to battery voltage and test for an open circuit.
- Test sensor B and its circuit against the manufacturer’s specification to determine whether the sensor is open or the harness is at fault.
Common fixes
- Repair a signal wire short to battery voltage or open wiring in the sensor B circuit.
- Clean or repair corroded or loose sensor B connector terminals.
- Replace sensor B if it is open or fails the manufacturer’s electrical checks.
- Clear the code and confirm plausible temperature readings and normal charging.
Can I keep driving?
Avoid charging while this fault is active if the vehicle reports a coupler or temperature warning, because charging may be limited or stopped. Driving may be possible if there are no other battery-system warnings; follow the vehicle’s instructions.
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.