Originally Posted by Effduration

Welcome.

FPR is Fuel Pressure regulator...I believe it is part of the fuel filter on the E53.

I happen to think all your issues stem from the parasitic drain that I don't think you have properly diagnosed and solved.. I am working on one myself at moment.

These cars really don't like low voltage and it leads to all sorts of warnings and strange behavior.



Using a multimeter set on the 10amp setting on the negative battery cable, you need to see amperage in sleep mode at 50 milliamps or less (= 0.050 amps). It is not enough to watch amperage drop when it goes to sleep mode. This is summary of the testing process..search on it...

You then need to test fuses measuring millivolts (not milliamps) to try and determine which circuit is causing the problem. There are several good videos on this...It may be your FSU, radio, any aftermarket electrical component, or something else.

Hopefully, A fully charged battery, fixing the parasitic drain and an EWS re-synch willl solve this.. But honestly, after that I think I would find a good non-dealer BMW specialist and let him/her fix it.