Codes: p0420 and p1415

[Thorinman]

My SES light has been on for awhile now and i hadn't got around to reading it until today. The codes read were P0420 and P1415
P0420: Catalyst System Efficiency Below Threshold (Bank 1)
P1415: Manufacture Control. Auxiliary Emission Control

I have read that P0420 will not set if P1415 is set. If that is true it sounds like my cat went bad then my drivers side air check value went out? I ordered two values today from gmpartdirect.

My question is do you think that the P1415 could have possible cause the P0420? I don't want to replace my cats if i don't have to.

Also is it possible that one of my O2 sensors could be causing the P0420? Should i try replacing those before the cat?

Thanks.

[0rion]

well, first off what year car is it? GM extended the warranty for the cats to I *think* 10 years and 100,000 miles but I'm not 100% sure on those figures, I just know it was extended. 420 is usually a bad cat. The check valves are known to clog. Start with the valve and go from there. I suppose they could be related but if the 420 comes back I would look at taking GM up on that warranty.

[Thorinman]

Its a 2002 Camaro z28. I have 105k miles on it. I will start with the values and go from there then. Thanks.

[2001NBMZ28]

Could be related since they're both bank 1, but seen posts where only one or the other is set by itself - you can look up the codes at gearchatter.com and get the info if they affect each other. The extended warranty on the cats is 10yrs/120K so you're cat is still covered.