What it means
The cell thickness sensor circuit for hybrid/EV battery pack B has a signal above the expected range. This indicates a circuit or sensor signal fault; it does not by itself indicate a cell voltage problem.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The BMS monitors the signal circuit for the cell thickness sensor in hybrid/EV battery pack B. This code sets when the signal is above its expected range, which can result from a short to battery voltage, an open sensor, or poor connector contact; it does not indicate high cell voltage.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
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
- Record freeze-frame data and view pack B thickness sensor live data to confirm the high signal and whether it remains fixed.
- Check for other pack B sensor circuit codes and compare available pack B and pack A readings to determine whether the fault is isolated.
- With the vehicle made safe according to the manufacturer's procedure, inspect pack B sensor wiring for a short to power and check connectors for corrosion or poor pin contact.
- Test the pack B sensor circuit for opens and unintended connection to battery voltage using the manufacturer's wiring information.
- Measure sensor output and circuit continuity against the manufacturer's specifications to isolate the sensor or harness fault.
Common fixes
- Clean and secure corroded or loose pack B sensor connector pins.
- Repair pack B sensor wiring shorted to battery voltage or an open circuit.
- Replace the pack B thickness sensor if it remains open or produces an out-of-range high signal.
- Recheck BMS readings after repair and perform any required manufacturer-specified calibration.
Can I keep driving?
A high pack B sensor signal can cause the BMS to limit propulsion or charging, so avoid heavy acceleration and keep any trip to service short if the vehicle remains controllable. Stop if the battery warning escalates, power drops sharply, or the pack becomes unusually hot.
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.