[Snertz]

You can use the AP to read all codes, no need for an extra reader. The AP is able to suppress the CEL for missing cats, once it's activated in the map there's no need to do it again periodically.

IIRC the OTS Stg2 and above maps have this function turned on already, but if it doesn't you can just activate it by opening the maps in AccessTuner Race and checking off the boxes for P29F4 and P29F5 in advanced engine parameters. P29F4 and P29F5 are the codes for missing primary cats.