What it means
The ECM detects a range/performance 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 reports cooling-system temperature to the vehicle control module, which checks whether the reading changes and fits the expected operating range. This code sets when sensor B's signal is implausible or does not behave as expected, even if the circuit is not simply open or shorted.
Common causes
Most likely first.
- Coolant temperature sensor B reading outside the expected range
- Poor sensor connection or sensor installation issue
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 compare sensor B's reported temperature with other available battery coolant temperatures and ambient conditions.
- Inspect sensor B's connector, mounting, and accessible wiring for looseness, damage, contamination, or incorrect installation.
- Watch sensor B live data from a cold start and during normal temperature change to see whether the reading is stuck, erratic, or implausible.
- Check the sensor B circuit and sensor response using the manufacturer's test procedure.
- Confirm the sensor is correctly installed and compare its output with the manufacturer's specification before replacing it.
Common fixes
- Correct a loose sensor B connection or installation issue.
- Repair damaged wiring or connector terminals in the sensor B circuit.
- Replace sensor B if its response remains outside the specified range with sound wiring.
- Clear the code and confirm the temperature reading changes plausibly.
Can I keep driving?
The vehicle may reduce power or slow or stop charging to protect the battery. Avoid demanding driving while 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.