2007 Volvo S40 Ambiant Temperature Sensor

There were some issues with the A-Pillar wirng harness where they could fret and cause all kinds of problems, one of them affecting the outside temperature sensor. Do this first, with the key out of the ignition. Open the drivers door and look in the hinge/door stopper area for the harness connector. With a flat tip screw driver if you look closely at the bottom you will see 2 red clips, one on eachside. With the flat tip screw driver, preferably a pocket screw driver, push in the red tabs to release the connector. Push the connector in and out several times to clean out the pins. reconnect the connector and start the car. If the reading for the outside temp starts to work you will need to replace the harness and would strongly suggest you have the dealership do the repair since it looks like you are still under factory warranty. If the harness is faulty, replacing the sensor will be a waste of time. And the sensor is under the drivers mirror which then you would need to unplug the drivers door module behinde the door panel, open up the connector and use a special tool to unlock the terminal pins from the connector to replace the sensor. Try what I suggested and let me know what happens.