Follow the metal coolant elbow from the left side of the motor (where the thermostat is) to the right side where it goes into the motor (near the coil), the temp sensor threads into the metal elbow right before it goes into the block.
190F
Didn't mention the year or engine size but temp sending units are generally found close to the thermostat.
To fix the temp gauge check the temp sending unit first. A bad sending unit is a common problem with the temp system.
it is located on the bottom end of the head
THE temp sending unit 4 the inside gauge usally has 1 wire & the sending unit 4 the Computer has 2 wires.
Next to the thermostat housing.
Which sending unit? Oil pressure sending unit? Engine temp sending unit? Fuel gauge sending unit?
The coolant temp sensor screws into the thermostat housing. This is located where the top radiator hose connects to the engine.
it screws into the side of one of the heads.
First try unplugging the coolant temp. sending unit and plugging it back in(may just be bad connection at the plug), next replace the temp. sending unit if the plug-in thing didn't work.
Replacing the gauge could be a costly job but it is seldom the gauge goes bad. More likely the temp gauge sending unit is at fault. Replacing the temp gauge sending unit would take less than 15 minutes.
more then likely it could be the temp, sending unit. or a bad wire to temp, sensor!!