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Home >> Jaguar >> 2019 >> XF S >> Repair and Diagnosis >> External Pages >> Different car >> Section 200 (Electronic Engine Controls - V8 S/C 5.0L Petrol, Project 8 -- XE/(760)) >> Electronic Engine Controls - V8 S/C 5.0L Petrol, Project 8 (G2261903) >> Description And Operation >> Electronic Engine Controls >> Description >> Ambient Air Temperature Sensor

Ambient Air Temperature Sensor

WARNING: This page is about a different car, the 2019 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.
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The Ambient Air Temperature (AAT) sensor is a Negative Temperature Coefficient (NTC) resistor that allows the Powertrain Control Module (PCM) to monitor the temperature of the air around the vehicle. The PCM uses the AAT input for a number of functions, including engine cooling fan control. The PCM also transmits the ambient temperature on the FlexRay bus for use by other control modules.

The AAT sensor is installed in the left exterior mirror, with the bulb of the sensor positioned over a hole in the bottom of the mirror casing.

The PCM supplies the sensor with a 5V reference voltage and a ground and translates the return signal voltage into a temperature.

If there is a fault with the AAT sensor, the PCM calculates the AAT from the temperature inputs of the MAFT sensors. If the AAT sensor and the temperature inputs of the MAFT sensors are all faulty, the PCM adopts a default ambient temperature of 25°C (77°F).

NOTE: Disconnect the startup battery when removing or installing the left door mirror. Failure to do this will cause the Ambient Air Temperature (AAT) sensor to provide an incorrect temperature of -40°C (-40°F). This prevents the Air Conditioning (A/C) from functioning until the vehicle has been driven for 10 to 20 minutes.
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