BMW Repair: scan codes, air sys, engine vacuum

Question
hello, i have a 528i e39. the check engine light came on.i have a ob2 scan tool(innova 3100).when i scanned it the codes p1421 and p1423 came up.i was able to find,secondary air system bank 1 for code p1421. i was not able to find the other code p1423.can you tell me what the sec. air sys.bank is,and how i might be able to fix it.and  the other code that i couldn't find. thank you very much.

Answer
Eddie, Ambient air is injected into the exhaust system upon cold start up for around 90 seconds to speed the heating of the cataylitic converters. This is the secondary air system. The air pump is in the front of the engine bay or behind the bumper, I cant remember it has a corrugated black plastic hose that connects to the non-return valve (Round silver shinny metal cylinder) bolted to the cylinder head. The non-return valve allows the air into the exhaust ports when it receives engine vacuum to hold the valve open. The small little black vacuum hose tears and breaks very often when it gets old. Replace as necessary. This is the most common cause. Let me know either way and fill out a follow up survey if you would.
-Evan