What Does P0AAE Mean?
The hybrid battery ECU has detected that the signal voltage from the battery pack air temperature sensor A circuit is below the minimum expected threshold. For an NTC thermistor sensor, a low circuit voltage typically indicates a short to ground in the wiring or a shorted sensor element. The ECU may interpret this as an excessively high air temperature and run cooling fans at maximum speed unnecessarily.
Common Causes
30%
Short to ground in the air temperature sensor A signal wire
30%
Failed air temperature sensor A with internally shorted NTC element
20%
Water intrusion or corrosion in the sensor connector creating a low-resistance path to ground
15%
Pinched or chafed wiring shorting the sensor signal to a ground or metal surface
5%
Battery ECU internal pull-up resistor or input conditioning circuit failure
Diagnostic Steps
1
Read the air temperature sensor A value on the scan tool. An extremely high temperature reading (well above ambient) with the vehicle at rest confirms the low circuit is being interpreted as high temperature.
2
Disconnect the air temperature sensor A connector. If the scan tool reading jumps to an extremely low temperature (or -40 degrees C), the short was in the sensor or downstream wiring. If it stays low, the short is between the disconnect point and the ECU.
3
With the sensor disconnected, measure resistance from the signal wire to chassis ground at the ECU connector end. A reading below 10K ohms indicates a short to ground in the harness.
4
Measure the sensor resistance at its terminals. A near-zero ohm reading confirms an internally shorted thermistor element.
5
Inspect the sensor connector and wiring for moisture, corrosion, chafing, or physical damage. Pay attention to areas near the battery cooling duct where condensation may collect.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The hybrid battery ECU has detected that the signal voltage from the battery pack air temperature sensor A circuit is below the minimum expected threshold. For an NTC thermistor sensor, a low circuit voltage typically indicates a short to ground in the wiring or a shorted sensor element. The ECU may...
The most common cause of P0AAE (Hybrid Battery Pack Air Temperature Sensor "A" Circuit Low) is: Short to ground in the air temperature sensor A signal wire
Typical repair costs for P0AAE range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A low circuit reading causes the ECU to believe air temperatures are excessively high, leading to maximum fan operation and potentially unnecessary power restrictions. While the primary battery cell sensors still provide direct protection, this condition wastes energy and may drain the 12V battery. Repair when convenient.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0AAE to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Battery Thermal Management
Difficulty
Type
Generic (SAE)
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