SES light comes on and temp gauge doesn't move intermittently
 

hey guys

im thinkin it's gotta be a sensor here

94 Z28
here's what happens

im drivin down the road on the way home from work, adn the SES light comes on. well im stuck in traffic at that time and i decide to see what temp im runnin. i notice the gauge is like 170ish, and id been drivin for like 25 minutes in traffic, we all know LT1's don't run that cold when siftin through traffic. it never went up.
so i keep drivin, cause nuthin seems wrong as far as running condition or anything. next thing i know, about 10 minutes later, the SES light turns off, and the gauge pops up to the temp.
this was the second time it happened. the first time, i put a JET PCM in there, was driving home from work, and the SES light came on, so I figured I'd take out the PCM...fast enough thing to do. Sure enough the SES light wasn't on when I restarted the car, so I figured that was due to JET PCM.
I'm gonna reinstall that thing now that the light came on without it on.

So I'm thinking maybe a bad engine temp sensor (or going bad)
Or maybe possibly the LT4 knock module I just installed.

So here's the short of it:
SES light comes on intermittently
while SES light is on, temp gauge doesn't work
SES light turns off and temp gauge works again after 10-15 minutes