Hey, Mys40t4 are you talking about the coolant temperature sensor?

Yes, I have the proper software installed on all components.

Thank you all for chiming in!

Thank you for the response. The check engine light is not illuminated and my Actron scan tool does not show any codes. Is it worth it to go to a Volvo mechanic and pay the $90 for them to scan the car for error codes, or is my basic scan tool going to tell me what I need to know? I know the actual l...

Have you had any luck solving your problem? I am having similar issues. As well as erratic idle.

I have a 2001 Volvo s80 2.9L non-turbo 77,xxx miles. It will run fine until it gets up to temperature. When it gets warm, the idle ranges from 200 rpm to 1500 rpm and will stall at times. I have replaced the ETM, PCV system, spark plugs, and ABS module (all with Volvo parts) and have traced all wire...