You'll see I have the same situation with the same readiness monitors. You'll see my threads regarding the problem but it's still unsolved after over a year. What I've noticed for sure is that my secondary air runs fine at cold startup and there is no blockage. However, the check for the secondary air, which occurs by running the secondary air momentarily at the first idle after the car has entered closed loop, does not run. I have not gotten any input from anyone as to why that won't run. I'm not focusing on the catalyst monitor as I believe that will only run after the secondary and egr monitors run. What I don't know is if the egr monitor needs to run before the 2ndary air monitor. My guess is that it should not. As I have access to another c280 (1994), it runs the 2ndary test at the very first idle after warmup every time. Please let me know if you have any success. My dealer and independent were not able to determine the problem.