Powertrain, generic · Fuel and air metering, auxiliary emission controls

P0070 Ambient Air Temperature Sensor Circuit A

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The ambient air temperature sensor A is an NTC thermistor whose resistance falls as temperature rises. Its value is used by the climate control, the outside temperature display and the engine control module, which needs it to enable other diagnostics and to correct its maps. Depending on the vehicle the engine control module reads the sensor directly, or the instrument cluster or another module sends the value over the data bus; some vehicles have no sensor and estimate ambient temperature from intake air temperature. P0070 is the general circuit fault or an invalid signal, for example when the instrument cluster reports the value as invalid or the reading is implausibly low.

Likely causes

Sensor faulty (exposed to spray and stone chips at the front)
Connector corroded or wire damaged, e.g. after front-end damage
Instrument cluster or data transmission faulty (vehicles with bus-supplied value)
Engine control module faulty

Symptoms

  • Wrong or missing outside temperature display
  • Climate control regulates incorrectly
  • Check engine light on (manufacturer-dependent)
  • Other monitors may not complete

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–200
Time0.3–1 h

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

Parts involved

ambient air temperature sensorambient air temperature sensor wiringinstrument cluster

Related codes

P0071P0072P0073P0074P00D9P0110

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov, en.wikipedia.org.