What it means
The ECM detects a high fault on the hybrid/ev battery pack coolant 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 pack coolant temperature sensor B provides a signal the vehicle control module uses to manage battery cooling and charging. This code sets when the signal is higher than expected, which can happen if the signal wire contacts battery power or the sensor circuit is open.
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 check sensor B live data for a high, fixed, or missing temperature reading.
- With the vehicle powered down according to the manufacturer's safety procedure, inspect sensor B's accessible wiring for damage or contact with a battery power feed.
- Check the sensor B connector for corrosion, loose pins, or an open connection.
- Test the sensor B circuit for an open and unintended battery voltage using the manufacturer's procedure.
- Test sensor B and compare circuit measurements with the manufacturer's specification before replacing components.
Common fixes
- Reconnect or clean poor contact at the sensor B connector.
- Repair wiring that is shorted to battery power or open in the sensor B circuit.
- Replace sensor B if it is confirmed open internally.
- Clear the code and verify a plausible sensor B temperature reading.
Can I keep driving?
Charging may be slowed or inhibited, and the vehicle may reduce power to protect the battery. Avoid hard acceleration if power is limited, and stop if a battery temperature warning appears.
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.