When I bought my 2017 540i the dealer installed a Dinan ECU. I've had a couple problems that weren't due to the Dinan ECU although this last time the dealer de-installed the Dinan ECU and I ran stock ECU for 30 days; the DTC didn't come back so they reinstalled the Dinan ECU. A few weeks later I get a P0299 code (supercharger/turbocharger underboost) that I've deleted but it comes back at no set time or operating condition.

The dealer has been unable to duplicate the fault so they just deleted the code again and mentioned Dinan is no longer supported by BMW.

One of the reasons I had the Dinan ECU installed at the dealer was because it was covered by BMW according to the dealer.