Volvo xc90 heat thermometer does not go above the normal limit even if the motor is overheating. Caused me a lot of money cause i didn't realize my motor was overheating. Is there anyone that knows how to fix that? Thank you

 

what year is your car? you can start by replacing the engine coolant temp sensor - the one under the thermostat. Then you can use a quality OBD2 reader to measure the temperature in place of the guage to see if all is normal. It will be hard to replicate an over temp condition. You may wind up needing to replace the gauge cluster if you think the guage is not reading.