williammease

I have a 2007 coupe with 70,000 miles and the fuel gauge/sending unit has malfunctioned over the last 6 months. Initially it would only act up when I completely filled the tank but now after sitting at idle for 1 minute the gas gauge drops from full to totally empty and that seems to trigger the dash message "Low Fuel", "Service Fuel System" and the "check engine light" sounds and goes on. After the car is driven about 1 minute the dash and gas gauge begin functioning normally but it takes a lot longer for the check engine light to reset. I was told this light is triggered by the number of engine starts after the problem is corrected.

Could this be a bad sealing gas cap or is it a tank sending unit that requires $1000++ disassembly of the rear of the car to change out?

KB9GKC

Hello,

Have you been using Chevron Techron every few fillups? Chevron Techron keeps the fuel system clean and your fuel level sensor operating properly.

Try a bottle at each fillup and see if the Chevron can clean the fuel level sensor.

Douglas in Green Bay

williammease

Yes, I have tried the Chevron Techron and the Lucas Fuel Cleaner every fillup for the last month. The frequency of the warning light and computer message appearing has increased!

HAD2HAV2

Just to chime in. I also have a 07 with 66,000. I filled up 2 weeks ago and the gas gauge went bonkers like yours. Check Engine also came on. After I burned a couple of gallons of fuel, gauge is working fine. Check Engine light went out. Filled up this past Monday. Same thing happened again. Pulled battery cable to make the CE light go off. Again, after burning 2 gallons of fuel, gauge is fine. My educated guess is the Sending Unit. Sucks. I have a Dealer 75,000 mile warrentry. Can't wait to explain this to them when I hand them the keys this Christmas to fix. Plan on filling up again tomorrow to see what happens. Will write back tomorrow night. Good luck.

williammease

That's exactly how my problem started about 6 months ago. The automated alarms and gauge malfunction would only trigger with a gas fill-up. After driving about 12 miles the gauge would begin functioning normally and after probably 8 restarts of the engine the "check engine" light would turn off. Obviously this problem has grown into a more bothersome issue but I realize there is no easy/cheap access to replace the sending until and I do not have the extended warranty to cover the $1,000+ repair estimate. I'm interested in your diagnosis and what GM will do to correct the problem. Don't wait to get this fixed!

torquetube

The second one. Pull the codes to confirm.

If it is what it appears, a bottle of Techron may help by cleaning the sensor, but in my experience it's not a cure.

williammease

I had PepBoys pull the codes and the only one that came up is: P2068 "Fuel level sensor 2 circuit high (symptom 00). Where do I go to find the recommended approch to correcting this problem? I guess this means I need to replace the fuel sensor that is inside the fuel tank and requires removing the rear differential to address.

Gearhead Jim

The Techron is kind of "step one" in trying to fix this cheaply, but along with that you should be sure to use a Top Tier (google) brand of gasoline. If already using Top Tier, try a different Top Tier brand for a couple of tankfuls along with the Techron.

The odds of this fixing your problem are not good, but the cost of tearing the car apart would make me try this first.

Also, there was a GM computer reflash that would solve the problem in some cars, but it may have been only for the 2005. Who can answer that one?

Good luck to you...

HAD2HAV2

I filled the fuel tank again. This time it was half full instead of near empty. Same result, needle goes to zero. I've already used Techron and changed gas brands. CE light did not come on until I shut the car off and started it again. Going to let the dealer deal with it along with the rockin' driver seat and the DIC information interior lights that quit working. Seems the list is getting longer. Cost to me, $100. The gas gauge problem sucks. Since this problem want strand me, I'll have these problems looked at when I'm on vacation at the end of the year.

williammease

That's the same problem I'm having. Maybe GM has a computer reflash that resolves this issue because I'm sure there are numerous others who preceeded us with this problem and GM would not want to spend $1,000+++ to replace each of these faulty sending units. I have only used premium BP or Sunoco gas since I bought the car new but the additives in todays gas may have something to do with this issue. Let me know what happens when you go back to GM and I'll see if there is a computer reflash fix.

cribbage

Fixed my problem. Not caused by non-tier one gas. That is BS. It is a cheap sensor. They cost a lot, $80+ and pull the rear end to get to tank. I have the bad sensor if you want pictures. In my opinion and after market can't be any worse than the original. Sorry to offend but the guts are cheap.

TXredc3

I would like to see pics. What's the procedure to get to the sensor?

Walterga07

Was interested in seeing other owners issues and results with this problem. Mine started at 55000 miles then disappeared till about a week ago... My dealership quoted
a fix to replace both fuel pumps as not a good idea to do one only at a cost of $4400:ie BUT being a regular customer they could do it for about $2400 ??? My C6 now has
70000 mi on it.. really never had problems that I could'nt take care myself.. I've been using BG fuel additives that my service advisor has given me an sometimes they work
and sometimes they don't.. My problems are all the same as everyone else...Looks like
something that GM hasn't addressed....outside of a making money issue for them..
I have always used a tier one fuel that has cleaning additives.. But have never have had these type of problems with my other model corvettes. Just looking for some direction as up till now this has been my favorite vehicle above the others... Keep telling my spouse that she can "plant" me in it when the time comes..

cribbage

The fuel pumps are not bad, they cost a lot. The sensor just attaches to the pump. Non-GM about $45, GM product about $75 or so. The problem is you need to pull the transmission, exhaust, etc. to get to tanks. The mechanic I had showed me the problem. I also had noise in drive train that turned out to be nut fell off of prop. shaft. I posted pictures of sending mechanics on the site, not sure if it is still here.

HOXXOH

I'd be highly suspect of that dealer who "quoted a fix to replace both fuel pumps", since there is only one. The $2400 "bargain" is still more than twice the fair price. Spend some time searching here for other fuel tank threads, before you make a hasty decision.

There have also been problems created by overfilling the tanks. the standard procedure is to not add any more fuel after the automatic shut off. I would suggest a test of only filling to the approximate 3/4 level for a couple of times, before resorting to more labor intensive options.

BRISLS1

I only have 20,000 miles on my 2007 Z06, and I have this problem, though not from over-filling the tank, I am too cheap for that. I only drive the car once a week, and I only ever get to about a half - 3/4 full with gas.

I really hope they have gotten good at fixing this kind of thing, because I am almost out of the Carmax Service Agreement (Maxcare maybe?), and there is of course the threat that coverage is not 100%, or at all for a fuel sensor.
Thanks for the tips on fuel additives, but time is of the essence for me given the above, so it was direct to shop, night-time drop-off, and call Uber for a ride home.

joliett

Same exact problem...I have base 2008, 150K miles. I always used cheapest Premium gas I could find. Just started with Techron, and it brought the gauge back to 5. I used 1 bottle when my gas gauge was below 1/2 tank. And then 2 additional bottles when empty. While full, I let the car sit with the Techron in the tank overnight and one day. Then I tried to keep the tank full by topping off the tank a few times with the Techron still in it, to keep the gauge cleaning itself at the full mark.

One service manager told me to be patient with the Techron...I'm now on my third fill up. Now the gauge only goes to zero for the first gallon or so. And improvement in the gauge is definitely noticeable. (But I now have BG 442 waiting to be tried.) The last fill-up, my gauge started out perfect, then dropped to zero, but recovered within a few miles. No check engine light this time too.

I wanted to give the Techron a fighting chance -, since I see improvement with every fill-up, before I use the BG. One or two more fill-ups without any additive will be the Techron's last chance.

I swear the Techron had the engine running so smoothly, I thought it was off - as I travelled down the Interstate at 75mph....there was no vibration at all.