Norval

Have been having this problem for years on my 2011 GLK 250 diesel.
On long trips (usually over three hours) my fuel gauge suddenly starts to go down quickly until it shows 0 and the low fuel warning light comes on, but there can still be over half a tank left. Still happening to me and is annoying. If I stop for a while at a rest stop sometimes it returns to accurate reading but then on the highway it drops rapidly again. I remember reading on the forum about 3 years ago someone else had this problem. Anyone know what causes it and is it a fault that Mercedes have introduced a fix for? Don't want to ask the service people before I know the answer...

Plutoe

You sound like a person who spends loads of time maintaining the car, therefore I would not be concerned because in ten years the tank will have rotted out and then you may pay attention to the problem!!


PS: you have a faulty fuel level sensor!!

bop11

Sounds like the sender unit has a problem. I think I have seen where someone has replaced their sender on this board. You are probably out of warranty, and it did not look like a difficult. Looks like they are anywhere from $75 to $105. The thread showed the sender put in from the top of the tank located under the rear seat?
Good Luck