Intermittent fuel gauge problem
 

Took our GLA250 on a long road trip from Indianapolis to Key West and back. Car performed great and averaged 30.5 MPG with cruise set at 77 MPH over the 3K mile trip. Ride was more comfortable than my wife's GLK. Car now has about 5K miles.

Ran into one problem with fuel gauge. We had been driving for several hours after a fill up on the way down to FL. Last time I looked fuel level was just under 1/2. Next time I checked it, needle was on absolute 0. I selected range on the dash info, and it now read "---". I stopped at the next exit and did several key on/off cycles, but gauge remained on 0. I then filled the tank. It only took about 8 gallons which was consistent with last fuel level before it died. After fill up, gauge remained on 0. Several hours later we stopped for a late lunch. On restart after one hour long lunch stop, gauge function returned to normal, and has worked correctly for last two weeks. I had made a service appointment at the dealership, but cancelled it figuring they wouldn't be able to find the problem if it is now working. Not too worried at this point since lots of warranty coverage remaining.

Anyone have any thoughts about what happened?

Am curious as to what your problem was. My 2009 is doing just about exactly the same thing but the first time it happened (last Christmas) 18 gallons of ULSD "fixed" the fuel gauge and remaining miles display. 500 miles up and 19 gallons didn't have a problem. Somewhere after 400 miles on the way home it happened again. I haven't put fuel in since and the problem is not going away. May visit the dealer tomorrow just for laughs. Not a happy owner. Have had more problems in 2 years with this vehicle than all other automobiles the past 15 years. 16 years ago I had a car which was scrubbing rear tires off every 20k miles.

Dealership cannot resolve fuel gauge problem
 

Finally took my car into dealer for another issue and asked them to check out fuel gauge. Gauge had been working correctly since the initial outage, so didn't know what to expect.

Turns out the car stored two codes showing that the gauge had indeed malfunctioned. Problem is the service manager told me Mercedes has not provided them with any diagnostics nor repair instructions for those codes. Best dealer could do was clear the codes and tell me to let them know if it happened again.

This happened to my wife on a long trip. Her GLA250 is still under warranty so we'll get it checked out.

Peter