I need some input from you Audi techs...

The 0411 code points to the secondary air injection (egr valve) and the 0422 code points to a bad catalyst, bank 1. My question is, can a bad egr valve, or vac hose going to it, cause the 0422 code? Is the EGR normally suspect, or is more typically a vac hose?

Previously, I had replaced the valve cover gaskets, plugs and wires, and coil packs... so I have eliminated a bad spark discharge as a suspect hopefully.

Any input would be most appreciated!

98 A4 2.8 fwd