Member, Sport: On DSC: Off
Join Date: May 2005
Location: Johannesburg, South Africa
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It is important to keep in mind the proximity of the sensor to the road surface. Over here in South Africa mine could read up to 5 degrees celcius difference between ambient and display readout. I have had my sensor renewed before I realised this so my sensor is quite new.
Remember that tarred surfaces in direct sunlight could heat up to 65 degrees celcius and over on a warm day. If my stock air dam is about 25-30 centimetres above road surface, the effect of your lowered suspension could be worsened two or even threefold on a warm day, with having the car at a standstill (say for instance at a traffic light) with no air flowing over the sensor your stated readouts are quite possible.
The sensor in question also controls the climate control system, so if your cc system is working ok chances are there is nothing wrong with the sensor itself. Your erratic readouts might be as a result of the sensor position, which, even on a standard E39, is not optimal.
2001 Imola Red II E39 M5 - Stock