Temperature gauge reading cold

Tempature gauge on my 2001 sierra (4.8) has been running low for awhile. The highest it will reach is round 160. It's currently running rough/rich and bad mpg. I replaced the ECT sensor but didn't help. I'm not sure if there are two ECT sensors on this model. I don't think it's the cluster. Is there a second sensor I'm overlooking?

Have you tried replacing the thermostat? If it is bad and stuck open it will cause the engine to run cold.

I have thought of that but figured it would be closed. That's probably my problem. Thanks for the help man

I'd also like to mention I've been driving this engine running cold for over 6 months. What else may I of damaged or any suggestions on anything I should check because of me driving it cold for so long?

Plugs could be fouled, explaining your running rough issue. The ECU is freaking out a little due to the cold temps.

As for the thermostat I have had them fail both ways. They are technically supposed to be "fail-safe" and fail open, but that doesn't always happen. One I had fail open actually came apart and I pulled out of the housing in two pieces.

I have uploaded a pic of my plug I just can't figure out how to post it..

I have uploaded a pic of my plug I just can't figure out how to post it..

Just google "spark plug appearance". You'll find pics of what is normal/abnormal.

Ok. Should I replace housing also or just thermostat?

Ok. Should I replace housing also or just thermostat?

Usually just replacing thermo is okay. Just don't over tighten and bust a bolt or crack the housing.

Ok thanks for all the help man

"Jiggle hole" faces up, highest point.

Thermostat fixed the problem. I really appreciate your advise.

good deal

That's what the forum is here for. Glad it was an easy fix.