GMC Repair: Check Engine Light, coolant temp, gmc dealer

Question
I have a Check engine Light that registers a Coolant Temp Sensor error code. It read that the air outside is hotter than the engine temp which is crazy. Now I had the engine temp sensor replaced and the check engine light removed. After some operation of my Envoy it returned again. Not only that but the fan is on full blast during starts now. It will only turn off after 20 mph speeds. My tach has been acting funny as well after the change. Now the speedometer will just die and any moment. It cause my car to accelerate when the cruise speed decrease eventhough the vehicle never lost speed. Is This common? and Do I need to address this with GMC Dealer service dept?

2005 GMC Envoy SLT 4.2l Inline 6 LL8

Answer
I would definitely take it back to the dealership. It sounds that you do have another sensor that has gone bad. I will say that seldom times, when we install new parts, they are bad from the manufacture. This leaves the customer thinking that a group of idiots worked on the second largest investment.

 It also sounds like you have other electrical issues as well. I could not find anything specific to your described problems, however, I did find other owners reporting the same problems. There may be a "campaign" for recalls on this issue.

I hope this was helpful.