Yesterday, my gas gauge on my '05 C6 went to empty (actual 3/4) and the "Service Fuel System" message appeared on my dash. The gas gauge fluctuated from actual to empty and everytime the same message appeared.

Later, my check engine light came on as well. Anyone else have this problem? Any suggestions?

 

I had almost the same thing about two months ago. I had put gas in the car and failed to tighten the cap all the way. The fuel system is a presurized system and the cap was letting pressure escape. I would take it by the dealer to have the code checked and reset. You can also do it yourself bith a code reader from a parts store. Any brand that is OBDII compliant will work. On Star can also access your code but they cannot reset it. Good Luck
Bill

 

You were right! I tightened my gas cap and it now works fine. Just have to stop by a Chevy Dealership to get the "check engine" light reset.

I appreciate your help!

 

I wouldn't bother taking it in to dealer just yet, if the gauge and car now seem okay --

"If the Light Is On Steady
You also may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. See Filling Your Tank on page 5-7. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap will allow fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed
should turn the light off." [Bold added]

 

This is a well known issue. It is a defective fuel card in the left tank. The dealer will replace the card or I have read where there might be a software fix. It happens to a lot of 05's built before
April 2005. They will turn off the dash light when they fix the problem. It will continue to happen until it is fixed. I had mine fixed last June as I have not had the problem since. Good luck and let us know how it turns out.

 

If the Check Engine Light is associated with a P0463 code there is a software fix (TSB 05-08-49-027) that corrects the problem. Takes about 30 minutes for a dealer to install it to the Engine Control Module.

 

I just went to Sarasota this weekend for a Car Show at St. Armand's Circle and filled up the tank in my 2005 C6(which was built either just before or in the beginning of April '05) for the first time. Guess what??!!! The same thing happened to me- all of a sudden the DIC said " Service Fuel System" and next I looked at the gas gauge and it was READING EMPTY?!!! I had only driven at this point about 45 miles non-stop. Then it kept reading full, then empty, full then empty.....etc. etc. The next morning the check engine light came on and then I opened up the gast tank cap, re-closed it (turned it 4 times) and the light went out and never came back on. However, the gas gauge kept reading empty and full, off and on again and so on all the way back home.
On the way home, I thought to call onstar and they diagnosed it as the trouble being a defective card in the left fuel tank. Tomorrow morning I will be going to the dealer to fix it. But On-Star did their job and also wanted me to call them back in the am so they could make the aptmt but I declined since I could do that easier myself due to my usual busy daily schedule. Keeping my fingers crossed for tomorrow.

 

After a couple rides... the check engine light went out and the gas gauge is also working fine.

Do you think that I have a defective "fuel card"? ... or was my issue just the gas cap, because now everything is working?

 

I would doubt it. I am pretty sure that it all related to the loose fuel cap. I would just drive it and enjoy it for a while. If you have a defective card it will show back up in the next 3 - 4 weeks.
Bill

 

I had the same problem last year - checking the gas cap, tank level didn't seem to change anything. The problem would come and go at random. It sounds to me like the fuel sensing unit (fuel card). Once the card was replaced, no prob.

Here's the original TSB:



Part Number CVN Description
12605740 00002555 New software with diagnostic enhancements for DTC P0463 and P2068.
Replaces all previous software.



Erratic Fuel Gauge Readings, Fuel Gauge Reads Empty When There is Fuel in Tank, DTC P0463 or P2068 Set, Low Fuel Message Displayed in DIC (Reprogram ECM) #05-08-49-027 - (Nov 18, 2005)
Erratic Fuel Gauge Readings, Fuel Gauge Reads Empty When There Is Fuel In Tank, DTC P0463 or P2068 Set, Low Fuel Message Displayed in DIC (Reprogram ECM)
2005 Chevrolet Corvette

Condition
Some customers may comment that the fuel gauge is erratic or reads empty when there is fuel in the tank. Also, the driver information center may display the "Low Fuel" message.

Upon investigation, the technician may find either DTC P0463 or P2068 set.

Cause
This condition may be due to the fuel level sensor over-traveling its ink path. When this occurs, the fuel level sensor loses electrical contact and sends the fuel gauge to empty. As fuel is drawn out of the tank, the fuel level sensor re-establishes contact and the fuel system operates normally.

Correction
First confirm that DTC P0463 or P2068 have been set and that no other fuel-related codes exist. If other codes are present, follow published DTC diagnostics.

A new software has been developed that adds a buffer to the electronic circuit that waits before it sets a fuel message or drives the gauge to empty. Technicians are to reprogram the ECM with this updated software calibration. This new service calibration was released with TIS satellite data update version 11.5, available November 13, 2005. As always, make sure your Tech 2® is updated with the latest software version.

 

The fuel gauge swinging from full to empty is a defective card and has nothing to do with the cap. The new software fix is a lot better than when mine was done. The fuel tank had to be removed.

 

That's what mine did. It would work fine for awhile and then would act up for awhile. It will not stop running, it's just annoying to see the gauge swinging up and down and the check engine light. If I remember the message was check fuel system.

 

That sounds like what I experienced... and yes, it reads "Service Fuel System".

BUT... why, immediately after I tightened the gas cap did it go back to normal if it had nothing to do with the cap?

Anyone else experience the same thing?

 

It's a random thing. I think mine did it more on a full tank. I lived with mine for a few months because the problem was new at the time and I wanted to make sure that the dealer would know what I was talking about when I took it in. Many members swore it was the fuel that was causing the problem because the C5 did have a problem with the type of fuel causing a similar problem. As it turned out the fuel has nothing to do with it. It is a defective card.

 

Thanks... when I researched this issue, I came across the C5 issue, which (like you said) seems to be linked to fuel.

I have a long distance trip planned in a couple weeks... I think that I will take it in and have the dealer read the code.

I appreciate your feedback!