I have an issue with my 03 A4 Avant 1.8T that causes the temperature to drop when driving on the freeway. I seems as though the thermostat is being held open somehow.

I have replace the engine coolant temp sensor and the thermostat assembly. Is there anything else I should look into? Would the radiator coolant temp sensor cause this to happen?

Thanks

Update:
I am at a complete loss. Now my temperature always drops down to the 1/4 mark if I drive >40 mph. I have replace both temp. sensors and the thermostat. Please let me know what I should look into.

 

Updated. Please give me some advice.

 

I've read a couple of posts that have this same issue. I don't remember seeing a good solution for it though. IIRC it usually comes back to a thermostat problem, either a bad thermostat (test before installing) or something like installing the thermostat upside down (the little ball should be up)

 

have u flushed the system out yet.

 

I have flushed the system.

I didn't think to test the new thermostat but it is the big electronically controlled thermostat assembly, not the usual small mechanical unit.