Once you get the menu unlocked you can watch the fuel levels.

At about 27L the right side should get down to about 1.4L and stay there.

As the left side drops to zero the left should stay at 1.4. (or whatever your car baseline is).

If the right drops below 1L (on flat ground; of course it will bounce around while driving), it means siphon not working properly.

The right should stay the same as the left drops all the way to zero.

Once the left hits zero the right will drop to zero (at that point you will have about 3.6L of fuel remaining).

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)