I hate to have my first post being a help post but, well I could use it.

I have an 05 A4 Quattro with a 1.8T. I noticed a small leak of coolant a few weeks ago, filled up, and only noticed a small decrease in fluid. I was driving two days ago and the Coolant light came on and the temp gauge spiked. I got the car home and heard the fan shut off about 10-20 seconds after the car was turned off. I did not see any steam (even though the car temp was in the red.) I checked the coolant reservoir and it still had plenty of coolant (although there is still a slow leak.) I took it out later to see get a better idea of what was going on. The car slowly creeps up to the halfway mark on the temp gauge and holds steady for a bit. After about 5 minutes or so the Engine temps spikes and the coolant light pops on again. When I stop the car at a stop light the temp decreases down to the halfway point again after about 20 seconds then spikes again down the road.

Any thoughts or help would be greatly appreciated (sorry I am somewhat of a noob at this)

Thanks!
Bash

 

Fix the leak and see if that fixes the problem. Most common leak is the coolant flange. Could also be leaking at the thermostat, or, the thermostat is not functioning, so I would look there second.

If it is the flange, be sure to replace the temp sensor at the same time. The thermostat is electronically controlled and if the sensor is off the thermostat may be too.