I changed my sensor gasket with full oil using a vacuum cleaner to keep the oil in. It's a very nice hack. I've used a few times now for various things like putting in a drain plug with valve.

Brake pedal sensor feels like your main issue but if you have the right scanner check that both gas pedal pots are reading opposite scales.

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