My bet; a bad connection on one of the myriad of hoses in the system. I think the test applies pressure so you can run the test to pressurize and then spray soapy water to locate. Also any leak in the fuel system so check the main tank seals under the back seat and those fittings. Look with your nose! You shouldn't be able to smell gas vapor anywhere under the car. Find gas smell you found the leak. Run the purge test

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