P0AB2
Hybrid/EV Battery Pack Air Temperature Sensor B Circuit Range/Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- A
- AreaHybrid propulsion
- B2
- FaultThe specific fault in that area
What it means
P0AB2 means the hybrid or EV battery control unit judged the signal from battery pack air temperature sensor B to be implausible. It is not a plain open or short circuit fault. The reading was stuck, drifting, or did not agree with the other pack temperature sensors, ambient temperature or the expected temperature after a cold soak. Sensor location and naming vary by model.
Symptoms
- Hybrid or EV system warning light on
- Reduced power or limited electric assist
- Battery cooling fan running loudly, constantly or erratically
- Reduced electric-only range or altered charging behaviour
- Poorer fuel economy on a hybrid
- Stored code with no other obvious symptoms
Possible causes
- Faulty or drifting battery pack air temperature sensor Blikely
- Damaged wiring or corroded, loose connector at the sensor or battery control unit causing a wrong readinglikely
- Blocked battery cooling air intake, duct or filter giving a genuine temperature difference between sensorspossible
- Battery cooling fan fault or weak airflow causing uneven pack temperaturespossible
- Sensor poorly seated or displaced in the pack airflow pathpossible
- Fault in the battery control unit's sensor input circuit or softwarerare
How to diagnose
- Read all stored and pending codes and note freeze frame data, including pack temperatures and ambient temperature when the code set.
- Look for related codes for other pack temperature sensors, the cooling fan or the battery control unit, as these point to the real fault.
- Compare live data from all pack temperature sensors and ambient temperature after the car has sat cold for several hours; they should be close to each other.
- Check the battery cooling air intake, ducts and filter for blockage, debris, pet hair or damage, following the model's service information.
- Confirm the cooling fan runs and moves air at the speeds the manufacturer specifies, using the scan tool's active test if available.
- Inspect the sensor wiring and connector for chafing, water ingress, corrosion and pin tension. High-voltage safety procedures must be followed and only trained technicians should work on the pack.
- Measure sensor resistance or signal against the manufacturer's temperature data, and check the wiring for resistance, short or open circuits.
- Check for manufacturer bulletins on the sensor or battery control unit for the specific model.
How to fix
- Clear any blockage and clean or replace the cooling air filter and ducts.
- Repair or replace damaged wiring, and clean or replace faulty connectors.
- Replace sensor B, ensuring it is correctly seated in the airflow path.
- Repair or replace the cooling fan or its control circuit if airflow is poor.
- Update the control unit software only where a manufacturer bulletin identifies an outdated calibration as the cause, or replace the unit if it is proven faulty.
Can I keep driving?
The car can usually be driven short-term, but pack temperature monitoring is compromised and power may be limited. Have it diagnosed soon, and stop driving if a battery overheating warning appears or the car goes into limp mode.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.