temperature gauge trouble

Can anyone help me on this one? 2000 Xterra, 100,000km's. My temperature gauge is acting weird... It normally always runs with the gauge just a needle width below the half-way mark. Recently the needle has been "flopping around" when driving - BUT not all the time, and it never goes above the half way mark... Fluids are fine and since the engine is not getting overheated, I'm assuming it's a problem with the gauge or an electrical connection. Can anybody tell me what to check/replace before I take it into the garage?

The first thing I would check would be the sensor. I have had very few gauges go bad on me. I'm not saying it doesn't happen, but it is rare enough and sensors often enough that I would go there first.

Just so you know, sensors usually complete the grounding circuit on the gauge. If they are starting to go bad, they will generally break continuity to ground causing the gauge to move erratically as contact breaks and is regained. I haven't looked at the diagram for the gauge yet to see if I am right, I am just basing this on work on other automobile gauges.

I am having the exact same problem. Did you ever figure it out? Out of the blue the gauge just started acting up. I have 83,000 miles on mine.

I had it fixed at my local garage. It was only a loose connection. The mechanic did the job in a few minutes and charged me $10 or something. No big deal... If I had more specifics on how he did what he did, I'd love to let you in on them -- but I trust these mechanics, so I didn't stick around to watch or anything. Sorry.