Hi, some time ago I had the same problem as you have. I took the car to Fiat service and they re-flashed the engine ECU. There was sw update from fiat solving this issue. They also recommended to use 99 oc. petrol instead of 95 oc. for Tjet. Since the update, I did not see the problem for 2 years. Btw is was mostly happening when the outside temperature was around 10 deg C. When it was around 0 or even under zero, it worked just fine.