[645Nm]

I had CEL/limp modes randomly after installing FMIC and it only happened on jb3 map 3 onwards (with increase in boost).

Double check the FMIC connectors (this was my problem), causing boost leak. Connectors were not properly sealed. I reinstalled the FMIC and the car has been running on high boost maps 6 & 7 without any issues.

I don't think it is the JB3 since you haven't had the problem before installing the FMIC.

You could do a BT scan but if the boost leak is due to the FMIC not being properly connected the BT might not show any codes (as in my case) after the car threw MANY random CELs.

Also check the DCI connections especialy the (filter closest to the radiator), which connector might have been pushed out when FMIC was installed.

I know it is a pain to take off mods before going to the dealer. So, i suggest to scan the car as soon as possible - perhaps there is an independent BMW specilaist close to you that could scan it?
Only after you are sure it is not the FMIC/DCI/charpipe connections or JB3 would I take it to the dealer.
In any case the scan will show up if it is the HPFP and if it is take off as many of the mods such as JB3 and DCI before warranty work.

What type of FMIC?

Good luck...