I am driving around today beating on the Duramax as usual. When I got home, I let it idle until the EGT was down to 300. As I was watching the gauge, just before it got down to 300, it jump up very quickly to 600, and stayed there bouncing the needle up and down +/- 50 degrees. The Duramax was still idling normally, so I am assuming the gauge was not reading the actual EGT. Has this happened to anyone else? The probe is about 1 year old. Seems too new to be bad already.

Isspro has had their conditioning boxes go bad..... and probes do go bad once in a while.


First thing's first.. check and doublecheck your electrical connections and the connections to the probe.


Also a passing VHF transmitter can cause that to happen (i know because i have used on in my truck and pegged the pyro on level ground empty at 60MPH)