P0073 - AMBIENT AIR TEMPERATURE SENSOR CIRCUIT HIGH

The AAT sensor is a device that has the purpose of changing the ambient air temperature to an electrical signal, then this signal is sent to the Powertrain Control Module (PCM) and changes the operation of the air conditioning system, and it also displays the temperature of the outside air.

The PCM also receives signals from the Coolant Temperature Sensor (ECT) and the Inlet Air Temperature Sensor (IAT). Importantly, the PCM examines the voltage from the AAT sensor and compares it to the readings from the AIT and ECT sensors at the time the power switch begins to operate after a long period of cooling. If the inputs vary widely, the DTC code P0073 OBDII is set. This code is usually caused by electrical problems.

• Check Engine light on.
• Air conditioning malfunction.
• The instrument cluster may not give an accurate reading of the outside temperature.

When the fault code P0073 OBDII is set, it means that one or more of the following issues have occurred:

• Ambient air temperature (AAT) sensor signal circuit open
• There could be a voltage short inside the signal circuit to the AAT sensor.
• The ambient air temperature sensor may be in poor condition.

To solve the problems caused by the diagnostic code P0073 OBD2, you must take into account the following:

• See the Technical service bulletins (TSB).
• Check the cables and respective connectors of the AAT sensor. Look for worn or defective cables. Also, check the terminals of the connectors for corrosion. Make necessary repairs and replace any defective components if necessary.
• If you find no problems in the connections, by using a digital ohmmeter set the switch to the on position, then disconnect the sensor and connect the positive cable of the DVOM to one connector of the sensor and the negative cable to the other connector. If the result of this reading is 0 ohms or infinite resistance, then the sensor is defective.