Ambient Air Temperature Sensor Circuit
Code P0070 indicates a problem with the Ambient Air Temperature (AAT) sensor circuit, which measures outside air temperature for engine and climate control operations. The sensor signal is either open, shorted to voltage, shorted to ground, or the sensor itself has failed.
What You Might Notice
- Malfunction Indicator Light (Check Engine) illuminated
- Air conditioning may not perform properly or cycle incorrectly
- Instrument cluster may not display outside temperature accurately
- Overhead console may not show outside air temperature
- Possible hard start or rough idle in extreme temperatures
Most Common Causes
- 1
Open circuit in AAT sensor wiring
A break or disconnection in the signal wire between the sensor and PCM prevents proper voltage signal transmission. This is the most common cause of this code.
- 2
AAT sensor failure
The ambient air temperature sensor itself has failed internally or the thermistor element is no longer responsive to temperature changes.
- 3
Short to voltage in signal circuit
The AAT sensor signal wire is shorted to a positive voltage source, causing the PCM to read an invalid high signal.
- 4
Short to ground in signal circuit
The AAT sensor signal wire is shorted to ground, preventing proper signal voltage from reaching the PCM.
How to Diagnose It
- 1
Check Open circuit in AAT sensor wiring — A break or disconnection in the signal wire between the sensor and PCM prevents proper voltage signal transmission. This is the most common cause of this code.
- 2
Check AAT sensor failure — The ambient air temperature sensor itself has failed internally or the thermistor element is no longer responsive to temperature changes.
- 3
Check Short to voltage in signal circuit — The AAT sensor signal wire is shorted to a positive voltage source, causing the PCM to read an invalid high signal.
- 4
Check Short to ground in signal circuit — The AAT sensor signal wire is shorted to ground, preventing proper signal voltage from reaching the PCM.
How to Fix It
- 1
Inspect and repair AAT sensor wiring
Check the wiring harness and connector from the ambient air temperature sensor to the PCM for damage, corrosion, or loose connections. Repair or reseat connectors as needed.
- 2
Replace AAT sensor
If wiring is intact and connections are clean, replace the ambient air temperature sensor with a new OEM or equivalent part. The sensor is typically located in the front bumper or grille area.
- 3
Test and repair signal circuit wiring
Use a multimeter to test the AAT sensor signal wire for shorts to ground or voltage. If found, trace the wiring and repair the damaged insulation or replace the affected section of the harness.
- 4
Clear code and verify repair
After repairs are complete, clear the trouble code using a diagnostic scanner and test drive the vehicle to confirm the code does not return and climate control functions properly.
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