which I suspect is temperature dependent so the idea of a temp logger is a very good one. Clear the codes and start when cold. Drive until it faults and see what temp. Then cool the ebox with maybe a cool pack or just leaving the lid off. I've had many many cases of computers iPhones and iPads freak out when hot.

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