I have an AP1 (MY 2000), with short ram intake and exhaust (cat back). I took it to Auto Zone and got a P0420 reading. Their print out reads as follow: catalyst system efficiency below threshold, air fuel ratio concern, air leak ne heated oxygen sensor, ignition system concern, faulty catalytic converter. Not sure if this is something that needs to be taken in or can it be a DIY. Some advice please...

 

How many miles on your S2K? The original cat lasts about 70K mi on average (At least on MY01 is went out at 75K). If you have more than that, I'd swap it out and also get a new Ox sensor.

Alternatively, you can try a test pipe with the cel fix and see if you still get a code. If so, you know the Ox sensor is part of the problem. You didnt specify if you are running a test pipe or stock cat. Give us some more specifics.

 

sounds to me like you probably just need a new O2 sensor

 

Yeah it has way more then 75,000 miles on stock cat, so I should probably just replace the O2 sensor and the cat...

 

Dont replace the O2. It's fine.

The problem is the efficiency of the cat.

Just get 2 spacers, put them in your cat, and be done with it. Cost about $8.00.

BTW I'm not guessing

 

That fix works like a charm unless you're concerned with the environment hehe. If you live in a state where they smog the car instead of plugging it in at the OBDII connector it will fail, however. Good luck!

 

Thanks Billman; where can I get the spacers and is it something a novice like me can do?

 

The spacers are actually spark plug spacers. In an auto parts store, the brand is "Help". The part number is 42008 i think. you need to drill one of them to 1/2 inch. you screw the drilled spacer over the O2, then the undrilled spacer, then the whole think gets screwed into the cat.