Car needs to be smogged VERY soon. Been to busy to fix the problem lately. Not exactly sure how I would fix it either. I'm currently running AWE's stage 3 kit with a full APR exhaust (downpipes, cat-back). The car has been running perfectly aside from a constant check engine light. The way it works in Cali is that it would be an automatic failure. Anyone out there running the same (or similar) set up and found a way around this CEL problem?

Codes are as follows....

16815 (P0431) Warm up catalyst Bank 2 Efficientcy below threshold

16805 (P0421) Warm up catalyst Bank 1 Efficiency below threshold

..along with a few misfire codes

16684 (P0300) Random multiple cylinder missfire detected

16686 (P0302) Cylinder 2 missfire
16689 (P0305) Cylinder 5 missfire
16690 (P0306) Cylinder 6 missfire
16688 (P0304) Cylinder 4 missfire

I would appreciate any and all help as the date is coming quickly. TIA

if it's the O2 codes for no cats .. use NON-FOULERS ..stfa and you'll find what those are.

I do not know the exact parameters for the readiness codes on the S4, I'll just post my experience.

Clear the codes, readiness codes will say not ready of course. Let the car sit over night. Start the car up, let oil temp get all the way up to operating temperature. Go out and drive, making sure to get into the 35-45mph range for a sustained period (5-10 minutes) and try to vary the gear you are in (3rd and 4th). After an hour or two and enough cycles through that speed, your readiness codes should be back to normal. If you can, bring your OBDII scan tool with you and just keep driving varying speeds/rpm in that range until they come back online. Has worked for me. Currently no CEL and my readiness codes are all "ready"

-m