I have an 05 xterra and the gas gauge is not working properly it cause the check engine light to stay on if i fill the tank the light after a few trips will go out but once tank reaches half a tank the light will come back on and if i idle for a min or so the gas gauge till go all the way down to empty and will remain there until gas is put in again. I have replaced the gas cap and that didnt help any other suggestions. [:@]

 

Bad fuel sending unit.