I have an 03 A4 3.0 Cab and the engine temp gauge is only moving 25% of the way up. This is after driving for 30 minutes so engine should be warm. Just started doing this. Coolant level is fine.

2-3 weeks ago it would go up 50%, as it has for the past 6 years that I have owned.

Is it the thermostat?

No need to reply - I found I had an air pocket in the line. Filled the pocket and the problem seems to be fixed