I am getting ready to replace mine because I have the code for engine does not warm up quick enough. I think my issue is not the T-stat but the sensor as I am still getting heat. I am going to replace the T-stat and the sensor at the same time.
I have a question, though; I do not see if your properly purged out air from the system. Just running the engine to operating temp will not normally purge the system as the air is trapped in the highest area of the cooling system. Since the T-stat is low on the 4.2, the purge process would need to be followed. This the information I found on the database I use for repair of my truck: run the engine at 1,000 to 3,000 RPM in 30 second intervals until it reaches operating temperature with the reservoir cap off. Let the engine idle for 3 minutes and let it cool. After the engine cools, add to the desired level. If your temp sensor is lying to the computer, you would never know. I can't believe that an engine even with the T-stat failed open would run that cold unless you were in arctic conditions.
