billmac

My three years old A6 greeted me with this error code upon starting it earlier today:

"Fuel tank system malfunction! Contact dealer"

The fuel gauge went blank (tank is full). Stopped engine and restarted, same problem. Drove to work and MMI started to ask about a gas station, etc... After a few more minutes driving, the fuel gauge came back to life and the error message on the main display went away. Arrived at work, shut off engine, restarted and error code went up and fuel gauge blank again. What gives?

I've attached a picture of the display. It's late, so I won't be able to call dealer until tomorrow morning, but I am worried this could be something serious that might leave me stranded (bad fuel pump?) or a fire hazard (fuel leak?).

Any ideas as to what may be causing this?

Thanks,
Bill

snagitseven

My guess would be a faulty fuel tank sensor. Shouldn't be a big deal to fix.

tenspeed

Try tightening the fuel cap. A air leak on a cap will turn on a emissions warning or CEL on other makes.

Totti808

I had this issue on my A6 MY12 which happened intermittently and I got it fixed under warranty. I cannot remember exactly the cause of this but the fix was kinda costly.

2014a6tdi

I'd guess it's the float inside the tank that sends the tank fuel level to the computer. I don't think that you need to worry about getting stranded or any sort of hazard.

Totti808

You are right. I have always ignored the issue and the car drove normally. The fuel level reading used to work again after 10 minutes of driving.

2014a6tdi

When I was in high school my summer job was working in a shop, specifically marine, but we worked on cars occasionally. One of these jobs came in and I dutifully got under the creeper, disconnected everything and finally took the straps off to lower the tank to get at the float (on top). Astute readers will note I omitted the most important part of removing a gas tank.

Well, before I knew it, I had what seemed to be a 1000 lbs of fuel tank falling on top of me with the gas flopping around side to side making it impossible to balance and yelling, "HELP, HELP, HELP!". It was a really crappy car too, and I also recall thinking, I don't want all of my friends knowing I was killed by dropping a gas tank on my head from a Toyota Celica or whatever it was.

Ah good times...good times. Not entirely sure how I'm here to talk about them (or why anyone would have employed me at the time), but, it was fun.

billmac

Thanks all for the tips. On that same night, I tried resetting the fuel cap to no avail. Since yesterday morning, problem seems to have fixed itself and has not come up again.

I talked to a service rep and he asked if I had just filled up the tank (something I did the night before) after being "almost" empty (ok, ok, mea culpa). He then went on with what we all know, but sometimes (in my case) tend to forget:

Debris at the bottom of the tank can hinder correct operation of the fuel level sensor after refills, something that usually clears by itself after a while. He also recommended using a low flow setting when filling up. All is good now.

Thanks,
Bill

snagitseven

Or by tightening the fuel cap, you solved the problem. It can take awhile or some miles for a warning message/fault code to clear itself.

hedgeclipper

Does that really still apply even when using Premium gasoline? I seem to always be that person riding in to the station on fumes.