Audi Repair: Car will only start when engine is cool, coolant temperature sensor, engine coolant temperature sensor

Question
Hi, I have an Audi A6, 2.8 Quattro, 2000 132K, the symptoms are: wont start after driving it for 10 minutes, will start with no problem when cool, when it does start (rarely) (when warm I assume) it will smoke and engine will shake for 5-8 seconds then shut down, another interesting factor is my temperature meter always shows cold (not hot or in the middle) simply sits on C. please help. Also I have to fill the water tank every two days but the car has no leaks, it just consumes it. Could it be the thermostat?

Answer
More tyhan likely this is an Engine Coolant Temperature sensor problem.  Replace the ECT and let me know how it works,  With reference to water loss, you need to find out if this is leaking out, or getting into the engine and coming out as steam...
Jan