1999 Z3 2.3 Roadster air pump

Can anyone tell me if the electric air pump for the emissions should run all the time or only at certain times, will it not running cause error codes and the service engine light soon to be lit?
Has anyone ever had the crankcase vent valve be bad from new? I had one installed now the mechanic says it's bad. How do I check the valve when it is new and out of the box before I pay to have another new one installed?

Thanks for any help with this.

The secondary air pump runs for less than a minute after a cold start.

Searching on SAP or "secondary air pump" will turn off additional info.

See page 6 for some tests:
http://www.bavauto.com/newsletter/20...newsletter.pdf

Thanks for the info.