It's cheaper and easier to just go with a quality LED bulb replacement. I have been using the BLESK festoon bulb in my 2005 e53 with stunning results and absolutely no errors for a couple years now (haven't had to replace them either). You can order them from HID Concept. Pre-facelift may show errors with these bulbs though.

Error-Free Festoon 37mm LED

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2005 X5 4.4 (Sterling on Truffle) w/sport everything
2011 Audi S4 (Prestige, DSG)
2012 Audi Q7 (Sport, S-Line)