For my case of breaking multiple fuel sensors, it was finally tracked down the fuel sensor being pressured / "squeezed" by the fuel tank. I suspect it was because I used to load VERY heavy stuff into the car (with the back seats folded), and that it pushed down the top of the fuel tank (located) underneath the rear seat), causing continues pressure to the fuel sensor till it breaks.

The last time I replaced the fuel tank, I screwed a long metal plate to plastic part of the sensor, in order to strengthen it. It's been about 2 years since the last change and so far so good.

I tried ignoring the problem and refuel base on the distance having traveled after each refuel. But it was unreliable and I really went out of the last drop of the fuel once, only across the street from the fuel station! So'd suggest to get it replaced and drive in peace. They are only about $100-200 each, if I remember correctly.

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Here's the Photo Album of my (sold) X3; Album of my (newish) X5 is on the way!
(WARNING: read this before you buy anything from Umnitza)