Hi there. I am having trouble with my audi a6 2014 2.0 tdi in cold start only. It looks fine for the first couple of minutes and after starts shaking a little bit and releasing white smoke with a fssss noise on the back. It sometimes stalls on Reverse. Has anyone had this problem? Thanks

Will probably need more information. White smoke is never good, potentially pointing to coolant leaking into oil. Is oil fine, no mayonnaise under the filler cap?

This time of year, then batteries tend to fail, especially if it’s over 6 years old. Put a multimeter on it at cold, not  running. You need to be pulling 12.4v minimum. If not, then it needs to be replaced, and eventually coded.

This will be Euro 5 diesel. Literally could be anything, leaking injector, glow plug issue, etc. Car needs scanned with VCDS to reveal DTC error codes, then go from there.

Is it losing any coolant? Does the smoke smell of diesel?

Hi thanks for replying. 
Battery has been replaced and coded. All 4 glow plugs has been replaced as well. I did check the oil filler cap and it looks a bit wet but not much.It doesn’t loose any coolant and yes the smoke smells diesel