2010 S5 Thermostat failure symptoms

[noggieS4]

Hi I have a 2010 Audi S5 V8, I want to know the symptoms regarding a Thermostat failure. My car acts weird in temps above 90F, RPMS raise to 900 and feels accelerated. Under 90F the cars drives perfect. No CEL's and 0 faults on VCDS.

Maybe coolant sensor? Where is located?

Thanks for your help!

[AWEs5]

Had my thermostat replaced about a month ago. Didn't even noticed any symptoms to be honest. Dropped the car off at a dealership for the 55K service on Saturday. Picked up the car on Monday. Car overheats on Thursday. Towed back to dealership and replaced thermostat and leaking motor mount. The car displayed message "park and leave engine running". Obviously overheating because thermostat was close to red. Left engine running for about 30 mins and temperature went back to normal. I started to drive and before I could pull out the parking lot, I can hear the fans going crazy so I parked and left engine running until tow truck driver came. Which was bout 1.5 hours. Car was running the whole time. So I am wondering if I did any further damage.