What it means
The ECM detects a circuit high fault on the hybrid/ev battery pack air 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 air temperature sensor B sends the control module a signal for the air temperature near the hybrid or EV battery, which helps guide battery operation and cooling. This code sets when the signal is too high for the expected range; an open circuit, failed sensor, or poor connector contact can leave the module with an unreliable reading.
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
- Check freeze-frame data and sensor B’s live reading against sensor A and ambient conditions to confirm the high-signal condition.
- Following the manufacturer’s shutdown and safety instructions, inspect sensor B’s connector for corrosion, loose or recessed pins, and incomplete seating; inspect accessible wiring for breaks or damage.
- Use the wiring diagram to test sensor B’s signal circuit for an open and check connector contact and ground integrity.
- Test sensor B with the manufacturer’s procedure to distinguish an open sensor from a wiring or connector fault.
- Compare circuit and sensor results with manufacturer’s specifications before selecting a repair.
Common fixes
- Fully seat and secure sensor B’s connector.
- Clean or repair corroded or loose connector terminals in sensor B’s circuit.
- Repair an open or damaged signal wire to sensor B.
- Replace sensor B if it fails the manufacturer’s tests.
Can I keep driving?
Because the module cannot use sensor B’s reading reliably, the hybrid system may reduce power, slow or prevent charging, or limit battery cooling. Avoid long or demanding trips and stop safely if the warning is accompanied by overheating or a severe loss of power.
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.