What it means
The control module detects a low signal in the hybrid battery pack air temperature sensor B circuit.
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 a temperature signal to the control module for the air around the hybrid or EV battery. This code sets when the signal is lower than expected, often because sensor B’s signal wire is shorted to ground or the sensor has failed.
Common causes
Most likely first.
- Signal wire shorted to ground
- Failed sensor
- Wiring or connector fault
Symptoms
- Hybrid system warning light
How to diagnose it
- Use freeze-frame data and live scan data to confirm sensor B is reporting an unusually low or implausible temperature compared with sensor A and ambient conditions.
- Power the vehicle down using the manufacturer’s safety procedure and inspect sensor B’s connector and wiring for damage, moisture, corrosion, or grounding against the body.
- Follow the wiring diagram to check sensor B’s signal wire for a short to ground and inspect its connector and ground connections.
- Test sensor B’s output or resistance using the manufacturer’s procedure to determine whether the sensor itself is pulling the signal low.
- Compare all circuit and sensor results with manufacturer’s specifications before replacing the sensor or repairing wiring.
Common fixes
- Repair a signal wire shorted to ground in sensor B’s circuit.
- Repair corroded terminals or damaged wiring affecting sensor B.
- Replace a failed sensor B.
- Restore a poor circuit connection or ground found during diagnosis.
Can I keep driving?
The hybrid system may restrict battery cooling or power when sensor B reports an abnormally low signal. Avoid demanding driving and get it checked promptly; stop safely if overheating, unusual battery behavior, or unsafe power loss occurs.
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.