Good afternoon,
I have a 2007 A4 T Q 2.0 6spd Automatic
Yesterday, my coolant light had begun to flash, however the coolant level is sufficient. The Gauge spikes and then drops to middle position and does so while the key is turned -but not cranked. It is very peculiar. I've looked - no leakage, fans turn on while vehicle is cold, AC & Heat both work fine. No water in oil, no leaks whatsoever. From overnight sit, vehicle Gauge still peaks at startup. Ran great during 250 mile trek earlier in the day, happened out of nowhere yesterday afternoon.

Any help or or comments in relation would be greatly appreciated.

 

Could be a defective temp sensor. Usually an easy fix. You can get these at about any autoparts store. Be sure to make sure it has a new retainer clip or get one because the damned things will break on you removing it. If you don't have a new one to put on it, you're dead in the water till you do.

3-PC MEYLE AUDI VW Coolant Temp Sensor Water Temp Switch W/ Clip 1009190017 | eBay