Have an engine code for a check engine light 1423 and 1411 for an Audi A6 Quatro 2001

P1411 - secondary air injection system flow too low Bank 2.
P1423 - secondary air injection system flow too low Bank 1.
Check vacuum hoses to combi valves ,
most common split air injection pump which is riveted with aluminum rivets,ck rivets if they coming out ,pump doesn't build enough pressure.
In this case take pump out and put bolts instead of rivets all around pump case.Repl. all rivets not only broken one.Bolts sold at HomeDepot , just find a needed size.