When pulling the trailer over the pass engine temp gauge will go up and all of the sudden it pegs hot and the check engine light comes on. Get to the top and pull over no boil over or loss of coolant and the gauge goes right down and everything is fine. I have replaced the hoses, thermostate, and had the radiator flushed. Any other sugestions??

 

I've got bad thermostats out of the box before..............other than that maybe the temp sending unit. Good luck.

 

Any update?

 

Closing due to a one time post. Last post was on 05-27-2009. Thread starter can reopen if need be.