What it means
The control module detects a low signal in the hybrid battery pack air temperature sensor A 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 A sends a signal representing the air temperature around the hybrid or EV battery to the control module. This code sets when the module sees a signal that is lower than expected, commonly because the signal circuit is pulled toward 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
- Capture freeze-frame data and inspect sensor A’s live reading to confirm it is abnormally low or implausible relative to sensor B and ambient conditions.
- Power the vehicle down using the manufacturer’s safety procedure, then inspect sensor A’s connector and wiring for damage, moisture, corrosion, or contact with ground.
- Use the wiring diagram to check sensor A’s signal circuit for a short to ground and inspect its ground and connector connections.
- Test sensor A’s resistance or output using the manufacturer’s procedure to see whether the sensor itself is pulling the signal low.
- Repair the identified circuit fault or replace sensor A only after confirming the relevant tests against manufacturer’s specifications.
Common fixes
- Repair a signal wire shorted to ground in sensor A’s circuit.
- Repair damaged or corroded wiring or connector terminals affecting sensor A.
- Replace a failed sensor A.
- Restore a poor circuit connection or ground identified during testing.
Can I keep driving?
A low sensor A signal can lead the hybrid system to limit power or battery cooling, so avoid strenuous driving and get the fault checked promptly. Stop safely if the warning is accompanied by overheating, unusual battery behavior, or reduced power that makes driving unsafe.
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.