No way of even guesstimating without first having diagnosed the issue, not to mention the year, make, and model of the vehicle. It could be a faulty fuel sending unit (which typically requires the tank to be dropped in order to replace it), a faulty gauge, a frayed or broken wire somewhere, a computer issue.... you gotta figure out what's wrong before a cost can be put to it.
Need to know the year, make and model to start with. There are several reasons the gauge is not working. It would have to be diagnosed to give you an answer.
are you sure it is not the sending unit
how do you fix a gas guage on a 1989 ford aerostar
Its probably the float in the gas tank that tells how much fuel is left in the tank... its sticking.
In most cases it is the sending unit located in the fuel tank that is at fault. Replacement is necessary.
Then fix it
small amount
Have you checked the gas floater in the gas tank?
The fuel sensor is in the gas tank and probably needs replaced, the tank will have to come out to fix it.
Could be bad gauge or float stuck in fuel tank
how much to fix a gas tank on a 93 grand cherokee?
You have to replace what is called a "gas tank sending unit". This is a electrical device that inserts into the gas tank. The part cost about $100. Plus you have to find somebody that likes to work on gas tanks.
Most fuel gauge problems are the result of a faulty fuel gauge sending unit located in the fuel tank.