What it means
The ECM detects a circuit intermittent/erratic fault on the battery charger b coupler lock position sensor circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
How it works
The battery charger’s B coupler lock position sensor tells the control module whether that coupler is in the required position for charging. The module monitors the sensor circuit for a stable, usable signal; this code sets when the signal becomes erratic or drops in and out.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Use a scan tool to review the code’s freeze-frame data and live coupler-lock sensor reading, noting whether it changes when charging is interrupted.
- With the vehicle safely powered down as specified by the manufacturer, check that the charger B coupler is fully seated and its lock moves freely.
- Inspect the B coupler sensor connector for incomplete seating, moisture, corrosion, damaged terminals, or strain.
- Inspect the sensor wiring and ground connection for damage or looseness, especially where movement or vibration could disturb contact.
- If the fault can be reproduced safely, monitor the sensor reading while gently checking the accessible harness for dropouts.
- Test the sensor circuit and ground against the manufacturer's specification before replacing the sensor or repairing wiring.
Common fixes
- Fully seat and secure the battery charger B coupler.
- Clean and firmly reconnect the B coupler lock sensor connector if its terminals are sound.
- Repair a loose or noisy ground connection in the sensor circuit.
- Repair damaged wiring or terminals causing intermittent contact.
- Replace the B coupler lock position sensor if its signal remains erratic after circuit faults are ruled out.
Can I keep driving?
Charging may fail to start, stop unexpectedly, or proceed more slowly, so avoid relying on this coupler for an essential charge until the fault is fixed. Stop charging if the connector or lock becomes hot, damaged, or unstable.
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.