Yep. That's the reason to clean or replace the valve.
Also, that small vacuum line that attaches to the valve goes to an electric valve mounted just below the intake manifold just in front of the firewall. The other end of the hard plastic line that runs on the right side of the valve cover is attached to the electric valve with another short piece of hose. Then there is another piece of hose that attaches the input side of the electric valve to a one-way valve and a piece of hose from there to a vacuum port on the intake manifold. These hoses are hard to reach and they're not exposed to the heat of the exhaust like the hose that attaches the hard plastic line to the SAP valve, so they're probably OK. But if you're bored sometime, you might replace those hoses, too.
BTW, I can confirm that the DSC compressor (ABS pump) is located on the inside of the left fender just below and behind the water valve on my 2001 530i. That's probably the first part you're were asking about, just as you thought.
2001 530i/5 S+P CDV delete/Akebono ceramic pads
M5 SSK/RedLine MTL/M5 rear sway bar/Bilstein HD
BMWCCA Member #337964
Last edited by Steve530; 11-17-2012 at 08:31 PM.