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Fixing a gas guage

I have a 2003 Impala at a little over 129000 and the gas guage on it basically has stopped working. When I start the car it shoots to the F line and doesn’t leave that spot until I turn the car off and then it drops to the bottom. What all is involved in fixing this type of issue?

The float in the tank might be stuck.

Crawl under the rear of the vehicle with a rubber mallet, and give the gas tank a couple of good whacks to see if that gets the gauge working again.


FWIW, my gas gauge reads low (never quite makes ‘F’, has about a half-tank when it first hits ‘E’, then slowly goes a little bit lower). I keep track of mileage since last fill-up just to make sure I don’t get careless (I usually fill when it reaches ‘E’) but I’ve cut it close and observed that the warning icon doesn’t light until it really is on its last 3 gallons, which tells me that the sender gauge is correct, that I need replace only the receiver gauge, an easier task.


You’ve come to the right place! I’ve done this.

Got time for a little story? Usually,what happens on these is that a part of the sender (in the tank) goes bad. The sender is attached to the fuel pump module.

It is a part called a “wiper” that has tiny “fingers” of metal that disintegrate and the sender becomes intermittent and inoperative. The wiper is on the float arm and “wipes” across a little grid (potentiometer ?) on the sender. That part is usually just fine.

The good news is that there’s an access plate in the car’s trunk floor (right side in front of spare tire well) that lets you withdraw the module and replace/repair the sender.

Here’s an example of the entire sending unit replacement.

Here’s some DIY videos…

I’m not sure if these are for 03 Impalas. Take a look.


Did the gauge become erratic for a while or did it suddenly just quit (as you’ve described)?

Gauge just stopped working and stays at full.

Usually when the sender wiper starts disintegrating the gauge goes through an erratic period before it quits altogether. You’ve got me wondering.

This is the last discussion about the erratic behavior of the fuel gauge level unit (Bert has 3 screen names);

To determine if it is indeed the sender, remove the panel CSA clued you to. Backprobe the purple wire at fuel pump/sender module. Ground purple wire, if gauge goes to empty you know the sender is bad. The whole fuel module will need to be replaced if that’s the case.

This OP has stated in many of his other threads that putting fuel in vehicle is the limit of his mechanical skills. He is going to have brake work done so he should just have them look at the gauge problem at the same time and see if he wants to spend the money.

The other solution is to check fuel mileage every time he fills up to determine how many miles he can go and not get below 1/4 tank and fill up before that.

Basically what I am doing now is everytime I fill up I reset the milage guage and when I get to around 150-170 miles I refill up as that takes it usually a little past half empty. It’s no real issue but am thking of having it looked at when the do the brakes next Friday.


You have given excellent information for testing the sender. I did not know how to do that.

This I don’t agree with, replacing the whole fuel module. I saw advice like that when I had problems with my sender several years, ago. I provided a link, above, for a new sender. My Bonneville is a similar set-up. I actually removed the sender from the pump module and replaced only the wiper on the sender (fuel level sensor), and reinstalled the sender and then the module.

The whole job was about a 2 beer (well, maybe 3) project and it didn’t require assistance for anything.
It’s been working for years, now.

That’s good to know about getting sender separately. Here I am, been at this for better than 35 years, work at the same shop for 20, and assume my parts folks know what they’re talking about. LOL! I guess we know about "assume’. Part of their mentality behind replacing the entire module, I believe, is that we’ll see the car for this complaint at 120,000 miles and at 121,000 the pump goes South, and the shop’s left holding the bag since we were “just there”.

That hasn’t been happened to my pumps, but I hear what you’re saying from a shop standpoint.

Get this. When I fixed my Bonneville fuel level sensor (same deal with trunk access), following an online blurb, I ordered a kit (GM# 15824379) from a GM dealer that was stocked everywhere for warranty repair of senders on trucks/SUVs and had a really low price (that happens when GM is paying through warranty).

I popped out the module, unclipped the sender assembly, popped off the push-on brass piece the holds the “wiper” and installed only the wiper from the new GM sender kit. Voila! It’s been working for years!
It was an inexpensive cake-walk for a DIY’er.

I’m not sure, but I think it would work on many models/model-years.