I have no clue but I went on a business trip for 2 weeks and I turn on car for the first time in two weeks and I see a gas light on....

I tried checking the gas door, filling gas to full tank and its still on...
Any advise?

(tried searched and found nothing close...)

 

goto the dealer; chances are your sensor is done. Does your gas-meter show a fulltank and go down as you drive? If it does, maybe you could try resetting your ECU? or just live with it.

 

actually it does not show full full tank its about bar below full tank most of time... is that the sensor? and which sensor?

 

The sensor inside your gas tank? I dunno what its called, but that seems to be the obvious answer. Hopefully they can just replace the sensor and not the entire gastank.