Fuel gauge goes up when car is off

The last time I filled up was about a week ago. It usually takes about 15 minutes after I fill up for the gauge to show what is actually in my tank.

But I was driving at a little under half a tank last night, then I drove this morning and it was over half. What caused it to go up since it's been awhile since I've bought gas?

Also, is it normal in cold weather for your temperature gauge to start out completely at the bottom peg and slowly reach its way to the middle while you're driving?

This is my first car, so I'm kinda clueless about everything. Thanks!

Junior Member

Thread Starter

Join Date: Feb 2011

Posts: 3

Hey guys, I just received my sisters 1997 honda civic after it was stolen and I had to get the ignition fixed. After I got it back I drove it over 50 miles to get it back to my house. After fueling the car back up I notice the fuel gauge does not lower when the car is turned off. I know usually the gauge is suppose to lower when the car is turned off. Also when I fueled the car I put only 3 gallons worth of gas and the lever shot back up to where it was before I drove the 50 miles. I don't know if the fuel gauge in the car is broken. What do you guys think?

Join Date: Sep 2009

Location: Sparks Nv.

Posts: 1,224

That sounds normal to me.. My fuel gage needle doesnt lower when i turn my car off either. (not a noticeable amount) Try filling up with gas and drive it for like 150 miles or so. and see if it lowers?

if it doesnt lower then you have a problem...

Join Date: Jun 2007

Posts: 10,023

It is designed to stay at approximately the same reading while the car is off. If you add (or remove) fuel while it is off it will go to the new reading when you turn the key back on.

Three gallons of gas is enough to go considerably more than 50 miles, so it should be higher than when you started.

Junior Member

Thread Starter

Join Date: Feb 2011

Posts: 3

Oh great. I wasn't sure if it was damaged when they messed with the ignition. Thx guys. I knew the honda got good gas mileage but wow lol. Also the light to show the gears; park, drife and reverse is out. It doesn't come on when I turn the head lights on. Its a fuse right?

Join Date: Jun 2007

Posts: 10,023

If the dashboard lights up when you turn the lights on it's most likely just the bulb at the shift handle is burnt out. If none of the panel lights work it's either a fuse or the panel dimmer control. Or every single bulb is burned out. Since it's not your car realize that some people just drive until they are all out.

Junior Member

Thread Starter

Join Date: Feb 2011

Posts: 3

sounds good. Thx Mk378 and daone for ur replys. I appriciate it.

Join Date: Oct 2021

Posts: 1

Hi guys, first time on this forum. I have two vehicles ['89 JDM CRX DOHC Si and '99 Lancer GSR AWD]. Both are currently displaying the same problem, fuel gauge reads full when ignition is off. The Lancer has had a new fuel sending unit fitted but this has not resolved things. As neither vehicle is used frequently, I disconnect the negative battery lead until I'm ready to use them. Your help to resolve this issue would be appreciated.

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The fuel gauge sender is a component that is found in the gas tank of most road going vehicles. The fuel gauge sender, also commonly referred to as the fuel sending unit, is the component responsible for sending the signal that operates the fuel level gauge in the instrument cluster. The fuel sending unit is made up of an arm, float, and a resistor that changes according the position of the float. The sender float is designed to float on the surface of the fuel inside of the tank. As the level drops, the position of the arm and float will shift and move a resistor which controls the display on the gauge. When the fuel sending unit has an issue it can cause the vehicle to experience issues with the fuel gauge, which can put the vehicle at risk of running out of fuel. Usually a bad or failing fuel gauge sender will produce a few symptoms that can alert the driver of a potential issue.

1. Fuel gauge behaves erratically

One of the first symptoms of a problem with the fuel gauge sender is a fuel gauge that behaves erratically. A faulty fuel gauge sender may cause the gauge to suddenly change positions, or give an inaccurate reading. The gauge may appear to be at three quarters, and then only a few minutes later will change to half full, or vice versa the gauge may appear to be full, only to have the gauge climb higher a short while later.

2. Fuel gauge stuck on empty

Another common symptom of a faulty fuel gauge sender is a gauge that is stuck on empty. If the float somehow breaks or becomes separated from the arm it may cause the fuel gauge to malfunction and become stuck on empty. A faulty resistor can also cause the gauge to read empty.

3. Fuel gauge stuck on full

Another, less common, symptom of an issue with the fuel gauge sender is a fuel gauge that is stuck on full. A faulty fuel gauge resistor can send a bad signal to the instrument cluster which can cause the gauge to permanently read full. This is an issue, as the driver needs to know the accurate fuel level of the vehicle as to not run out of fuel.

The fuel sending unit is not a routinely serviced component, usually only serviced when it, or the fuel pump fails, however it does play an important role to the proper operation of the vehicle. If you fuel gauge is displaying any of the symptoms, or you suspect that there may be an issue with this unit, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the fuel gage sender should be replaced.