Burning smell after shut down the engine when stop start system is not working
I bought A3 SE 1.6TDI S TRONIC on 30 September.
2days ago when I drove, I noticed the stop start system is not working. And after arrived destination shutting down the engine, there was small vibration, sound from bonnet and burning smell also. Vibration continued around 5min.
This was happened yesterday also. Burning smell come off always when the stop start system was not working.
This morning same thing happened when I drove the car to kids school.
So I decided to go Audi service centre. However there was no problem with stop start on the way to Audi also when shut down the engine.
Technician said no problem.
Do I need to leave this issue?
Or better ask Audi to check more detail.
Kindly give me advice.
Thank you for your attention.