P0AACHybrid/EV Battery Pack Air Temperature Sensor A Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Air-cooled hybrid batteries carry a thermistor in the cooling air path; GM calls sensor A the inlet air sensor. The battery controller uses it to run the fan and to judge cooling. P0AAC is the general circuit code, set for an electrical fault that is not classified as low, high or erratic. No manufacturer documents this exact code publicly; GM reports the siblings P0AAD to P0AAF instead, with Type B, two-trip logic. CARB requires hybrid component temperature sensors to be monitored like other input components. If the controller has no valid air temperature, it typically falls back to fixed fan control and may restrict battery power. Check connector and wiring at the air inlet duct first, then the sensor.
- What you may notice
- Check engine or hybrid system warning light
- Battery cooling fan runs constantly or at fixed speed
- Reduced electric assist in hot conditions
- Likely causes
- LikelyLoose, corroded or damaged sensor connector or wiring at the air duct
- PossibleFailed air temperature thermistor
- RareBattery controller input or reference voltage fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.