Battery pack air temperature sensor A internally faulty (reading low); Sensor signal wire shorted to ground or to the sensor return; Damaged, corroded or water-affected connector at the sensor or battery control unit; Chafed or pinched harness near the battery pack or its mounting points; Fault in the battery control unit's sensor input circuit or reference supply; Outdated or faulty control unit calibration, only where the manufacturer has documented it for this model.

P0AAE

Hybrid/EV Battery Pack Air Temperature Sensor A Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
A: AreaHybrid propulsion
AE: FaultThe specific fault in that area

What it means

P0AAE is a generic powertrain code meaning the hybrid or EV control unit has seen the signal from the battery pack air temperature sensor 'A' fall below its expected electrical range. This usually points to a short to ground or a failed sensor, rather than the pack genuinely being very cold. The exact sensor location and number of sensors depend on the make, model and battery design.

Symptoms

Hybrid or powertrain warning light on
Reduced electric assist or reduced power
Battery cooling fan running constantly or not at all
Poor fuel economy or reduced EV range
Battery charge or discharge limited
Other battery temperature codes stored alongside

Possible causes

Battery pack air temperature sensor A internally faulty (reading low)likely
Sensor signal wire shorted to ground or to the sensor returnlikely
Damaged, corroded or water-affected connector at the sensor or battery control unitpossible
Chafed or pinched harness near the battery pack or its mounting pointspossible
Fault in the battery control unit's sensor input circuit or reference supplyrare
Outdated or faulty control unit calibration, only where the manufacturer has documented it for this modelrare

How to diagnose

Read all stored codes and freeze frame data, noting any other battery temperature or cooling fan codes and the conditions when the fault set.
Compare the live reading of sensor A with the other battery temperature sensors and with ambient temperature; a very low or implausible value on one sensor suggests a circuit fault.
Follow the manufacturer's high-voltage safety procedure before touching anything around the battery pack; only suitably trained staff should work on it.
Inspect the sensor wiring and connectors for damage, moisture, corrosion, bent pins and chafing, and check that the battery cooling duct and intake are clear.
With the sensor unplugged, see whether the live value changes to the open-circuit value; if it does, the sensor or the wiring beyond the plug is shorted.
Check the sensor resistance against the manufacturer's temperature table, and test the signal wire for a short to ground and the reference or return for continuity.
If the wiring and sensor are good, check the battery control unit's supply and ground and look for any applicable manufacturer service bulletin.

How to fix

Replace the battery pack air temperature sensor if its resistance is out of specification.
Repair or replace the shorted or damaged section of harness, using the proper method for the vehicle.
Clean, dry or replace corroded or damaged connectors and terminals.
Clear any blockage in the battery cooling air path so readings are accurate.
Repair or replace the battery control unit only if the fault is confirmed in the unit itself, or apply a manufacturer calibration update where one is documented for this fault.

Can I keep driving?

Medium severity

The car can usually be driven short-term, but power may be limited and the battery may not be cooled or protected properly. Get it diagnosed soon, and stop if further warnings, overheating or a loss of drive appear.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.