My ECT was doing the same thing for a long time, it always said the car was running too cool. Replaced the sensor and now it's accurate. It's a cheap and easy fix, I'd just pop a new one in and see what happens.
spoke to a few other members about it... And thats exactly what im going to do lol.
now that you mention it.... I think its been wrong since i have owned it!!! Its always said it was cooler than believable. But now it may have finally went faulty.
I Hump things for fun. Otto the Grand prix... Stupidcharged with bolt ons and stuff.