Powertrain, generic · Hybrid propulsion

P0AAF Hybrid/EV Battery Pack Air Temperature Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Open signal or ground wire between sensor and battery controller
Connector at the air inlet duct loose or with pushed-back pin
Thermistor open internally
Battery controller input fault

Symptoms

  • 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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery pack air temp sensor awiring harnessbms

Related codes

P0AAEP0AACP0AADP0AB0P0AB4

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.