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      08-01-2016, 08:15 AM   #13
stevenc
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Drives: 2015 BMW M4 Alphine White MT
Join Date: Apr 2008
Location: Houston, TX

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When you have downpipes, the car will throw a code. The JB4 is setup to delete the codes right away so you never see the code. When you disable to JB4 to go for emissions, the code will return and you will not pass.

You need the BMW computer to think you have stock downpipes. You either reinstall the stock downpipes or you try the mini cat / O2 simulators which try to trick the BMW computer into thinking you have stock downpipes.

Bottom line is you will have to do something in order to pass any type of emissions test.