"Trouble Code - P0420 Catalyst System Efficiency Below Threshold (Bank 1)"

I have an aftermarket GMG exhaust with cats. My question is does GMG, or any aftermarket seller/fabricator, need to comply with the 8year federal warranty (http://www.epa.gov/obd/pubs/420f09048.pdf)? I sent an inquiry to GMG but haven't gotten a reply yet so I'm still waiting. My plan is to see if GMG can just provide me with the cats. In the meantime. Try Seafoam. Try Techron. Do my 40k and swap plugs. Maybe swap O2 sensors. Did I miss anything?

Just curious. Thanks.

 

get some of those sensor extensions, work pretty well.

 

^^^ Like he said. Sometimes the extensions work and sometimes they don't. I would think that they would if your exhaust is already catted, and they even work sometimes with no cat at all.
http://vibrantperformance.com/catalo...oducts_id=2009 - These ones are good for tight clearances and they have different size restrictor fittings that will limit the amount of exhaust gas that gets metered. Relatively cheap too. No welding or anything just screw them in and tighten down the jam nut with washer underneath. I've had plenty of good experiences with them. Also, on a side note. You only need to install them on the rear oxygen sensors on both sides seeing as those are the only ones that monitor the catalyst efficiency. Just to be clear.

 

Absolutely not. The only reason the aftermarket cats usually fail is from excessive heat/excessive rich conditions. I've had magnaflow HF cats come apart on me within 4k miles on the street. I would also recommend 02 extensions to try first. You can buy them online for 50 bucks or so. As above the good ones have platinum/rhodium in the housing and have various threaded bends to fit most cars/areas.