P0AAF code meaning
Hybrid/EV Battery Pack Air Temperature Sensor A Circuit High
Powertrain system Generic code P0Axx codes Check engine light
What P0AAF means
Air temperature sensor A is the thermistor GM places at the cooling air inlet of air-cooled hybrid packs. Being an NTC type, a high signal voltage means the controller sees implausibly cold air, typically from an open wire or a lost ground. GM's 2013 table 13OBDG05C sets P0AAF above 4.63 V, equal to about -45 °C, in 7 of 10 samples; the two-mode hybrid tables of 2011 and 2013 use a reading below -45 °C in 30 of 40 samples. All are Type B, two trips. The controller then ignores the inlet value, so fan control and the inlet-to-outlet comparison lose their reference. Check the connector at the inlet duct for a pushed-out pin first. The shorted counterpart reading as very hot is P0AAE.
P0AAF at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0AAF
- Check engine or hybrid warning light
- Scan tool shows inlet air near -40 °C regardless of weather
- Battery fan runs on a fixed default speed
Common causes of P0AAF
- Most likelyOpen signal or ground wire between sensor and battery controller
- PossibleConnector at the air inlet duct loose or with pushed-back pin
- PossibleThermistor open internally
- Less likelyBattery controller input fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery pack air temp sensor aWiring harnessBms
What each part of P0AAF means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| AF | The exact fault in that area. |
What to do next
- Note P0AAF and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0AAF
What does P0AAF mean?
P0AAF means "Hybrid/EV Battery Pack Air Temperature Sensor A Circuit High". Air temperature sensor A is the thermistor GM places at the cooling air inlet of air-cooled hybrid packs. It is a generic code, so it means the same on every make.
Is it safe to drive with P0AAF?
Drive gently and only to a workshop. With P0AAF the car can go into limp mode (reduced power) to protect itself.
Will P0AAF fail an emissions test?
Yes, it can. P0AAF is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0AAF to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0AAF clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.