W210 P0410 message

[dubadaddy]

Guys,

Have and issue with my '97 w210.

Code is P0410 and I have replaced switch over valve, check valve, both bank 1 and 2 oxy sensors. Check for vacuum leaks, none. Secondary air pump is working. Cannot get rid of check engine light. Took to an indie and he check voltage between sensors and they check off as good. Indie says ports in heads are working and clear.

What the h#@#? Really need assistance on this one!

Sea foam job?