: I think that this is normal. My '87 325iC does the same. The OBC thermometer must be sensitive to radiant heat from the road, etc. e.g When my car is parked in the sun on a hot summer day (90+ degrees), it is not unusual for my OBC temp to show a temp of 120+. As soon as I start driving, it will gradually creep down to ambient temp (this takes 5-10 minutes). By the way, my old '94 Dodge Caravan had an OBC with a thermometer and it behaved the same way as my 325iC.