P0BC2
Hybrid/EV Battery Temperature Sensor E Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- B
- AreaHybrid propulsion
- C2
- FaultThe specific fault in that area
What it means
P0BC2 is a generic powertrain code meaning the hybrid or EV battery control unit has detected a fault in the circuit of temperature sensor 'E' in the traction battery pack. The control unit saw a signal outside the expected range, such as a voltage that is too high or low, or a reading that is implausible compared with other sensors. Which part of the pack sensor E monitors, and exactly how the fault is judged, depends on the make and model.
Symptoms
- Hybrid or EV system warning light on, plus the malfunction indicator lamp in some cars
- Reduced power or the car going into a limited performance mode
- Reduced regenerative braking or reduced electric-only driving
- Cooling fan for the battery running loudly or constantly
- Reduced charging speed or charging refusing to start
- Fault appearing intermittently, especially with temperature changes or road vibration
Possible causes
- Damaged, corroded or loose wiring or connector at temperature sensor E or the battery monitoring modulelikely
- Faulty battery temperature sensor E (open circuit, short circuit or drifting reading)likely
- Fault in the battery monitoring or battery control module that reads the sensorpossible
- Moisture or coolant ingress into the sensor harness or connector inside or near the battery packpossible
- Damage to the harness from previous repair work, impact or vibration chafingpossible
- Outdated or faulty control unit software where the manufacturer has a known fixrare
How to diagnose
- Read all stored and pending codes and note any other battery temperature, voltage or isolation codes, as these point to a shared wiring or module fault
- Read freeze frame data and check how the fault was set, including battery temperatures and ambient temperature at the time
- Compare live data from all battery temperature sensors; sensor E should be plausible against its neighbours after the car has sat for several hours
- Follow the manufacturer's high voltage safety procedure before touching any battery pack wiring, and only work on it if trained and qualified
- Inspect accessible wiring and connectors for damage, corrosion, moisture, bent pins and poor terminal tension
- Wiggle-test the harness with live data on display to look for sudden jumps or dropouts in sensor E
- With the system safely isolated, measure sensor resistance and circuit continuity against the manufacturer's specification, as values depend on the model
- Check for software updates or technical service bulletins for the battery control module on that vehicle
How to fix
- Repair or replace damaged wiring and clean or replace corroded or loose connectors
- Replace the faulty temperature sensor or the sensor assembly as specified by the manufacturer
- Dry out and seal any moisture-affected connectors and find and fix the source of water or coolant ingress
- Replace the battery monitoring or control module only after wiring and sensor have been proven good
- Update the control unit software if an applicable manufacturer update addresses this fault
Can I keep driving?
The car can often be driven for a short time in a reduced power mode, but the battery cannot be properly protected from overheating without this sensor, so have it checked soon. Stop driving and seek help if you see a red warning, smell burning, notice unusual heat from the battery area or the car loses drive.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.