My differential bolt snapped and the diff nearly fell out. I had bolt ons (dinan pulley, intake, ESS tune, MPE exhaust), but was fully covered under warranty as there was no evidence of abuse. Someone from BMW NA came out and took a look at the car (and presumably the ECU, given every other story about diff issues) and gave it a clean bill of health. I did flash back to stock using the portable ESS FlashLoader (highly convenient and can keep in your glove compartment) prior to being towed into the dealer.
Originally Posted by HighandDry
True, you can flash back to stock, but BMW is going to be able to see how many times the car was flashed. I would think that warranty is going to be voided- correct me if I'm wrong.
There was a case of a 911 where warranty was denied because the car was previously flashed. The ECU's are probably different than BMW's, but Porsche was able to see that it was previously tuned even though it had the stock flash on it.