I have a 1999 Dodge Ram 4x4 2500 Diesel. The Temp gauge does not work, and it idles high (about 1100 instead of 750 to 800 rpm. I have replaced the Temp Sensor sender on the front of the block, and a Truck Shop replaced the Temp Sensor sending wire and soldered the pins to the connector. It still does not work correctly.

It started intermittently, and ran correctly when started cold (50 degrees F or lower). However, after warming up, shutting down, and restarting, the temp gauge did not register, and it idled high. It also has a slight lag at acceleration. Otherwise, it still runs.

Any suggestions would be appreciated! Thank you.

 

Plug in with a scanner, and see what the PCM thinks engine temp is......