What it means
The ECM detects a low 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 for charging control. The control module sets this code when sensor B’s signal is lower than expected, which can be caused by a signal wire short to ground, an internally shorted sensor, or a poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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 capture freeze-frame data, including sensor B’s reported temperature and charging state.
- With charging stopped, inspect sensor B’s connector and harness for chafing, moisture, corrosion, backed-out pins, or a wire grounded against the body.
- Check whether sensor B’s reported temperature is implausibly low compared with ambient conditions and other available sensor readings.
- Following the wiring diagram and required safety procedures, test the sensor B signal wire for a short to ground and check connector continuity.
- Test sensor B and its circuit against the manufacturer’s specification to separate a shorted sensor from a wiring fault.
Common fixes
- Repair a signal wire short to ground in the coupler temperature sensor B circuit.
- Clean or repair corroded, loose, or pushed-back sensor B connector terminals.
- Replace sensor B if it is internally shorted or fails the manufacturer’s checks.
- Clear the code and verify a plausible temperature reading and normal charging.
Can I keep driving?
Do not charge while this fault is active if the vehicle warns of a coupler or charging problem, because charging may be prevented or interrupted. Driving may be possible without other warnings, but follow any battery-system instructions shown by the vehicle.
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.