So on my 93 Civic when I start the car my gas gauge will read the correct level until my car has been running for a while, then it jumps to Full and stays there. I tried resetting my ECU by removing the negative battery terminal and that didn’t work. PLEASE HELP!

 

sounds the Yellow/white wire is rubbing on the chassis somewhere between the gauge and the tank.
Either that or the gauge itself is bad.

if you have a volt meter check the voltage on the yellow/white wire at the rear of the cluster when this happens. if it's ground or less than 1 volt then the wire is the problem. If its 1V-5V and still reads full then replace the gauge.

 

will that make it go from normal level to full?

 

yes either problem could cause this...
if the wire is shorted.... ground = full to the gauge.

 

Or your level stick can be bad.

 

I found out it was the sensor in my tank, does anyone know how to change it or how much it cost?

 

On an old s-10 chevy it was 25$ from a parts truck, and like 1 1/2 days to change. May be simmilar? :dunno:

 

Pull off the lower part of your rear seat (10mm bolt just to the drivers side between the lower and upper part of the rear seat then roll it forward and up to pull out)
replacing the sender...


nevermind the special tool, a screw driver and a good wack of a hammer or your hand works great.


**EDIT**
price from a dealership is ~$50, junk yard can't be more than $15 if you pull it.