Trailer lights not operating correctly, and rear PDC coming on when a trailer is connected. You can defeat the beeping by turning PDC off manually.

Since the vehicle doesn't know a trailer is connected, trailer stability control and rear camera features may not work correctly either.

While a gt1 may be able to code it I would want the benefit of the most recent software, which means the dealer.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue