Hello Folks!!...;
An odd thing happened to me today.... My gas gauge was just below a half, so I filled her up. I reset everything and I noticed that my gauge didn't move. I reset everything again, but to no avail. I shut her off and pulled my key out, put it back, turned it and the gauge went from almost empty... right back to just below a half... What in th' Wide World of Sports..... All my other gauges are working fine. I've had her for a little over 7 weeks (although she spent just over a month there after Arm Wrestling with the Dealer and Warranty Company) But on other fills she worked as expected. Now I've heard some noise up here about the Aux battery... One time when I first got it... It said (Info Center) that I had an Aux Battery Fault or failure (or some such). But nothing since. And where pray tell is this little gem??....
Thank you for your consideration
Befuddled Freddie...

 

If you have aux battery in dashboard, it is for gear selector backup only.
One in the trunk is for ECO restarts.
Either way, no connection to fuel gauge.
Not sure about your model, but those cars have saddle shaped tank with 2 level sensors, so not easy to deal with.
Some of those tanks have extended warranty, although I think that was for W211 gasers.
If you have SD you can try if you will read the sensors separately.
1/2 showing on full tank looks like 1 of the sensors failed.
I would reset the meter at fill up and drive per miles in the mean time.

 

Geez, interested to see how this gets fixed. In the meantime, be sure to keep a log of your mileage and how many gallons it takes at fill ups. Hate to see you run out of gas due to a faulty gauge.

 

See attachments, all you should need to know inclusive of future reference.

 

Thank you konigstiger for the pdf's. It makes more sense when you can see a picture. But guess what..... I filled it up yesterday and reset everything while stopped, not moving, started her up and she popped right up to the full mark. Now I'm really confused. However, I'm really happy to see it working properly. We'll see what happens......
Thank all of you for your replies.
Fast Freddie

 

[QUOTE=hafferf;7496178]Hello Folks!!...;
An odd thing happened to me today.... My gas gauge was just below a half, so I filled her up. I reset everything and I noticed that my gauge didn't move. I reset everything again, but to no avail. I shut her off and pulled my key out, put it back, turned it and the gauge went from almost empty... right back to just below a half... What in th' Wide World of Sports..... All my other gauges are working fine. I've had her for a little over 7 weeks (although she spent just over a month there after Arm Wrestling with the Dealer and Warranty Company) But on other fills she worked as expected. Now I've heard some noise up here about the Aux battery... One time when I first got it... It said (Info Center) that I had an Aux Battery Fault or failure (or some such). But nothing since. And where pray tell is this little gem??....
Thank you for your consideration
Befuddled Freddie...

[/QUESTION]
I'm experiencing a similar problem with my 2007 E350. My fuel gauge stop working while I was driving. I can still drive my car with no other problems. I heard it's possible to reset the fuel gauge fuse. Question: Is this true & where is it located? wdmyles1235@gmail.com

 

I'm sorry to hear about your problems.

On the other hand, mine works so well these days I can see the gauge drop while I'm driving

 

FWIW 221 discussion some recommend Techron: https://mbworld.org/forums/s-class-w...auge-saga.html