Techee,
well first you might want to look at the light that is lit up, it should indicate which system it is related to, drive will have a drive related pictogram like a wheel with a thermometer, the hydraulic will have a gear with a thermometer in it most likely. Determine which system it is related to, then go to that motor and disconnect the sensor wires and see if the light goes out. The sensor wires should be on the end of the motor closest to where it mounts to the drive unit or pump depending on which motor it is.
It may trigger a code because of disconnecting it but the temp light should go out. Once you reconnect it the code (if one comes up should clear). Reason i say to try this is to see if the problem is actually the sensor itself or a short in the circuit that could be wiring related or possibly a logic or motor controller issue.

Hello! Usually engine temperature sensors works with resistance. so you can replace original sensor with the normal resistant but you need to now correct resistance. what is your lift truck correct model or give serial number?

I have the same issue with an EP25 forklift. Called service after looking into the problem they told me that it's the engine temperature sensor that is faulty. Problem is there is no spare part. Only fix as they say it's to replace the entire engine. I am still searching for solutions as the forklift only has 1000 hours work time.