What it means
The circuit signal for hybrid battery temperature sensor E is lower than expected. The code does not by itself identify the failed component.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Hybrid battery temperature sensor E reports the temperature at its assigned point in the high-voltage battery pack to the control module. The module sets P0BC4 when sensor E's signal is lower than expected, which can reflect a grounded signal wire, a shorted sensor, or a poor connector contact; the code alone does not identify which part failed.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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
- Save freeze-frame data and compare live readings from sensor E with the other battery temperature sensors, since an implausibly low E reading helps confirm the fault pattern.
- With the vehicle powered down as specified by its service information, inspect sensor E's connector and accessible harness for corrosion, damage, or a wire rubbed through to ground.
- Check that the connector pins are clean, correctly seated, and gripping their terminals; corrosion or poor contact can pull the signal low.
- Using the manufacturer's wiring information, test sensor E's signal wire for an unwanted short to ground and check continuity through the circuit.
- If the wiring and connector pass, test sensor E and its circuit against the manufacturer's specification to distinguish an internally shorted sensor from a remaining harness fault.
Common fixes
- Clean and properly seat corroded or loose sensor E connector terminals.
- Repair the signal wire where it is shorted to ground.
- Replace hybrid battery temperature sensor E if it fails the specified test.
- Clear the code and confirm sensor E tracks plausibly during a follow-up scan.
Can I keep driving?
Avoid hard acceleration and heavy charging, and stop if the vehicle limits power or displays an urgent hybrid-system warning. An unreliable battery temperature reading can trigger protective operation and may prevent normal charging or reduce electric range.
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.