A6 1999MY 2.5Tdi Quattro Auto Fuel Gauge

[JimSharp39]

Another question (to which I suspect I already know the answer to...a bad earth), but I'll ask it anyway in case it's a common fault.
I bough this car recently wtih a couple of acknowledged faults - one of which was a fuel gauge which occasionally stuck at 1/4 full. I filled it up to the brim for the first time this weekend. and the gauge immediately swung like a crazy thing from full to empty until I'd done about 100 miles. at which point it stopped swinging and is now stuck at full.
Bad earth? Duff sender? All of the other gauges appear to work correctly.

Any thoughts or is it a common fault?

Best,
Jim

[frosen]

Hi,i think you should try to open gas tank pull out that thing and clean it.
Thats my idea.