If your fuel gauge has been misbehaving, then it may be time to replace the sensor in the gas tank. Inaccurate readings, showing that the tank is always full (or empty) are sure signs that it is time to replace the sensor. The hardest part of the job may be accessing your gas tank. The sensor is placed in the top of it and depending on your make and model of car, that may be the most time consuming part of all. Once you are there, it will take about 10 minutes to replace the sensor in the gas tank.
Disconnect the negative cable from your car's battery.
Mark the top of the tank at the sensor with the locations of the three terminals on the top of the sensor. You will use these marks to make sure that your replacement sensor is lined up correctly when you install it.
Disconnect the three wires from the top of the sensor (the ground, power and switch wire). Do this by pinching the wire at the connector attached to the sensor terminal and pulling it off. If your sensor has the wires attached using brass screws, use a Phillips head screwdriver to loosen the screws, turning them in a counter clockwise fashion, and pull the wires from the screw.
Gently pry up the locking ring/gasket around the old sensor with a flat head screwdriver. With the locking ring/gasket removed grab the sensor and remove it from the gas tank, some cars will have a sensor that is screwed in place so if you cannot easily lift it from place, turn it counter clockwise until it comes free.
Insert your replacement sensor into the tank, turning it clockwise if it needs to be screwed in. Make sure you return the locking ring/gasket to its place and that the terminals on the new sensor are lining up with the chalk marks of the old. Especially if you have the kind that screws in, it may take a few tries before the alignment is correct.
Reconnect the terminal wires and the negative battery cables and you are done.
