Causes for temp gauge variations on 94 civic?
 

I was hoping someone here might be able to steer me in the right direction. I own a 1994 Honda Civic DX 1.5. About a month ago I started getting variations in the temp gauge for the first time in 13 years of ownership. This first couple of weeks the gauge would immediately shoot up to 1/4 warm on a cold startup. Then after another couple of weeks of doing that, it would immediately show 1/2 warm on a cold startup. Now after about the 6th week, I'm getting fluctations all over the place while driving around.

I haven't changed the coolant in about 42,000 miles (About 7 years ago). Yeah I know, not good, but it is what it is.

I'm on a really tight budget and don't want to throw the kitchen sink at this, should I just start with a radiator flush and see if that makes any difference? Then if that doesn't work consider replacing the thermostat or coolant sensor? If so, in which order?

I really appreciate any advice, thanks!

Of course the first thing to do is to check the coolant level. Check in the radiator when the engine is cold. It should be completely full. Don't just look in the plastic bottle.

coolant level is fine. Guess I'll be changing the thermostat or coolant sensor, just not sure which.