I need some help from you guys. Few days ago I got a Check Engine light on my 2007 WRX TR. When I took to a mechanic he said coolant issue. The gauge on the dashboard displays hot when idle while the ECU says its cold and it starts revving up. Our first guess was coolant or coolant sensor issue. He replaced both and we are still seeing the same issue. He is now saying it could be ECU problem itself. He is just taking guesses. The car is unusable at the moment.
Any ideas what could be wrong? or anyone run into similar issues?