Frustrated with the secondary Air Injection

[meran]

I am new to this site. Your hel or advise will be appriciated. I have a 1996 S500 coupe with 92,000 mi. Several months ago the Engine light came on and it read the P0410. The injection pump, valves openning and closing were checked by MB mech. the lines were replaced. the fuses are fine as well. I cleared the code and the engine light and the same code comes back. have been chasing this problem for months now. I need to get the inspection done but with this situation it fails. please advise. thanks in advance.