Originally Posted by jp99

The center plastic component just above those hoses comes off - it holds the pollen filter and, at firewall, fits into two ventilation ports. Once off, you have ready access to the back end of those rotten hoses.

1. Pull the long rubber gasket that seals the area - runs parallel to the firewall the width of the engine compartment.
2. Pull rain catchers (or whatever they are) on each side of the pollen filter area - pull straight up - each is about the size of your hand - they are snap-in, vertically.
3. Locate large nut that holds your battery positive cable in place - locate similar nut on the other side of the engine - that one does not appear to hold anything. Remove nuts, pull the plastic housing straight back off the bolts and lift out. Bolts will stay in place. That center housing, with pollen filter on top, comes out as one large piece - note how it fits back in at the firewall.
4. You should have easy access to the back ends of those hoses. In my case, the back ends had standard BMW hose clamps while the front, top ends had crimped clamps. The crimped ones come off readily with a screw driver to pry at the crimp point or, better, pry the wrapped part of the clamp up and back.
5. Replace hoses, reverse assembly procedure. I bought the two hoses at local dealer and got, also, two clamps to replace the crimped ones.

Ran quieter and smoother, took care of P1159 and P1161 fault codes. The replacement hoses are modified from the original but the parts guy had no idea if they were any better. I doubt it - looks like something that needs to be done every 4 or 5 years.

Good luck - post back if you have a problem. Fun project.