I hate it when dealer mechanics say "it's normal, all cars do that", whether they are right or wrong. They are usually wrong.After the trip, I took it to the dealer, the dealer told me it's normal, all cars do that. This is the only car I've owned the temperature gauge would fluctuate almost 20 degrees. It has been 8 years, and it's fine.
Poor connection at coolant temperature sensor, corrupted CAN data, you name it. What kind of vehicle is it? What faults are stored after CEL come on?Any idea what would cause the temp gauge to drop, then shoot back up to 80? runs fine then "slips" drops down to 40/30 for sec or two then back up to 80. service engine light comes on