I wonder if someone can help me out... My engine will not heat up much past the low mark on the H2O temp gauge, even when towing. I think the check engine light is probably related to this issue. As far as I can tell, the thermo must be a "fail open" type. Is this the original thermo? I bought the X used so I'm not sure if this is a factory part or not. If I just go to the local parts store will the O.E.M. thermo also be a "fail open"? Do I have to order a special one? I like the safety of not having a $20 part turning into a $2500 problem. Other than guzzling more $2.60 regular gas than normal (and the heater never getting that warm) am I hurting anything? How do I reset the idiot light? I tried to unplug the battery but it didn't change anything. Thanks.