The temperature gauge in my 2008 Maxima (3.5L engine) is always at cold. I used the OBD-II and the real time ECT gave normal reading. How should I fix it? Thank you.

 

If you have heat and OBDII gives you the correct reading, it's either your gauge cluster, the temperature sensor that gives the reading to the cluster, or the wiring from the sensor to the cluster. Most likely is the sensor, but do a quick visual check of the wiring and make sure the connector is fully plugged into the sensor as well

 

My car only has 1 sensor. I didn't see any broken cable. So I think it likely to be the gauge cluster but I don't want to waste money on replacing that for just the coolant temperature gauge.