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Temperature Gauge

The temperature gauge on my 2002 Nissan Sentra, for no apparent reason and at unpredictable times (when cold or hot, night or day, while air is on or off) but usually not my first drive of the day, will suddenly jump to a hot reading. This has been happening for some time. For other reasons, I recently had the ECU replaced; still the gauge jumps without reason. I am able to return the needle to normal by knocking on the glass over the gauge (a couple of knocks and the needle jumps back to normal). My Nissan dealer insists that the only solution is replacement of the Temperature Gauge Assembly at a cost of $506.35. What do you suggest?

I suggest you save $506.35 and keep tapping on the glass (it’s plastic, not glass) over the gauge when this happens.

Alternatively, you could install an aftermarket coolant temperature gauge for WAY less than $500.

Has anyone tested to coolant temperature sender?

You do need a gauge, but do you have to have one in the instrument cluster? You can buy one from any auto supply that will mount elsewhere. If you can’t install it yourself, ANY INDEPENDENT shop can do it for you. Total outlay, under $100.

You might also consider one from a salvage yard, or taking it to a specialized auto electrical shop to see if they can track down a wiring fault. Obviously it has one or whacking it upside the (speedometer) head would have no effect. I had one on a Neon a while back that was fixed by putting a wad of duct tape behind a wire bundle where it exited the dash and entered the instrument cluster.

The ECU usually has its own sensor for the coolant temperature so the dash gauge and its sensor has nothing to do with the ECU. There may be a problem with the lead to the sensor near the gauge. Since you can effect the problem when it happens I would inspect the gauge.