Hello everyone!

I'm sure it will quickly become obvious that this is my first post. For instance, after much searching I did previously find a thread that contained info about CEL codes and promptly registered so I could post... and then never found that thread again!! Such a noob!

Anyway, with apologies if this isn't the proper place to post this, I will get on to gettin' on with the questions.

I have a 2001 SLK320 that is new! <--to me anyway... Actual miles on this V6 are 90k. Owned the car about a month before the check engine light(or CEL to all you savvy people ) lit up. I immediately came to these forums to seek help in a voyeuristic, unregistered typa way... I found out from threads that Auto Zone would allow free checks of the CEL diagnostic codes and for that cool tidbit I am already thankful as I ran down this morning to an Auto Zone here in San Jose and got just that...free diagnostics!! Yay! And thanks again! Also in that same thread was an explanation of what a couple of the "codes" meant. Mine came up with four codes, as follows:
P0170 / P0173 / P0412 / P0403

the 170 & 173 codes were actually explained in the same thread I had read and lost track of and had to do with the Mass Air Filter, although it was also mentioned that a dirty gas cap O-ring might produce the same codes... ?? Sure enough, the diagnostic printout I got from Daniel at AZ was having to do mainly with the MAF.

The P0412 readout included jargon about a "secondary air injection system valve A malfunction". ??

P0403 regarded the EGR valve faulty or failed.

I guess my question really is whether anyone may know if all these codes are somehow related. It's either that or I am lucky enough to have a bunch of things fail concurrently!! Eeek! I hope that ain't it!

Any help at all would be appreciated, including suggestions for a trustworthy South Bay shop/mechanic, the best place to buy replacement parts(I assume here?), or even a more proper place to post this query if it ain't here!

Thanks a bunch in advance!!

~Gin

P.S. - I should mention that after "clearing" the codes, the CEL remained off for 3 consecutive starts, after which it has now lit up brightly again.