Dirty ECT and fubared autometer guages ?

I got a code 21 the ECT, pulled the old one out and it was dirty on one side. It looked like a sludgy oil build up. After that the cooling fan came on when the car was started and worked great. Once again the problem has come back 2 or 3 days later. I did not pull codes or check the new ECT to see if it is dirty but WFT?! This is on a new engine.

I put the new autometer oil pressure and coolant temp guages in tonight. I had the wires backwards for the guages. Oil press in the coolant temp and vice versa. The oil press was pegged at 100psi. So I fixed them and let the car run. Oil pressure was kind of jumpy and the movement wasnt exaclty fluid. Eiter the guage is messed up or my oil pressure is. Think that could have damaged the guages ?

Some sludge on the ECT will not cause a code 21 to set. I would look closely at the ECT connector and its harness for problems.

Gauges: Oil pressure will change quite rapidly with RPM at low RPM, although I wouldnt call it "jumpy". No idea if you damaged the gauges or not.

Thanks for the reply Jeff, the more I think about it..if both sending units run off of 5v then it probably just got the wrong signal. They do seem to work fine but I have not verified that either.

I had the car at 210, tried the "wiggle test" on the wires. That did noting, then I unplugged the ECT and the fan turned on. It did obviousley effect the idle of the car with the ECT unhooked. When I plugged it back in the fan turned off. Does this indicate anything ?

fan coming on is probably a failsafe so it doesnt overheat or something.

I pulled the upper intake, @ about 150* I got 1.14 on the green wire(feed?) and .04 on the black(return?). Sound normal ? I will see if I can search for the answer or have anything in the shop manual, too bad I don't have the EVTM.

Checked voltage to an article Pete D sent me a while back that I forgot I had, seems right. Hooked up to pull codes KOER and the fan did not come on, power to both yellow wires at the IRCM, I can only think of unplugging the battery and resetting the computer. I doubt thats the issue but thats all I can think is left.