1988 Honda Accord temp gauge

[dsh401]

The temperture gauge is stuck past the Hot mark only comes back down after turning the car off. This just started happening, nothing has been worked on lately. Gauge stuck on Hot, can let it sit for a day and start it up and bam straight to hot. What is the problem and how much would it cost to fix?

[mpumas]

You either have a bad sensor or an open or disconnected wire from the guage to the sensor. Probably a bad sensor. The guage is a bridge circuit that goes to full hot when the resistance of the sensor or sensor wire goes high. So if the lead is open or not connected or the sensor is bad, the guage will go to full hot.

[mpumas]

You can test the wire to the sensor by shorting the wire at the sensor to ground. If it is the sensor, the temperature will drop to minimum.

[dsh401]

Where is the sensor?

[mpumas]

It is near the thermostat housing at the top of the engine near the top radiator hose. There is a single wire attached.