Service engine light is on for PO420, so i'm guessing i need an o2 simulator, where can i buy one or is their a better solution to the problem?

 

Spark plug defouler works & its only $5

 

Is your cat deleted? Is so, yes.
Unless you rather replace your faulty cat or add one.

 

@Zambo - Did you delete the cat or replace it? If it's the stock cat, this is probably a sign of the cat failing.

If you deleted or changed the cat (and this applies not just to a high flow cat but non-GM factory replacement for stock spec) can throw this code. Ways of dealing with it are:
- Get a GM/OEM cat (probably next to no one's favorite answer)
- Pay to have the PCM re-tuned and delete the code (basically the PCM will not know to set that code)
- O2 simulator (but this only works for certain cars, and at that I heard is unreliable). I think 3800 Parts | 3800 Performance Parts | 3800 Series 2 Performance Parts - W Body Store sells them
- The spark plug de-fouler trick (you space the probe of the O2 sensor out of the exhaust stream)

Best answers if you were to ask me:
- Tune the PCM (but it's pricy if this is ALL you're doing)
- Spark plug de-fouler (look in the Dorman Help isle at the parts store, google it to see what you have to do).

I was prepared to do the defouler trick if my high flow cat kicked that code (never had to, got the PCM tuned instead). But I have read of MANY people who did the defouler on various makes/models of cars with great success and it's freakin CHEAP!

 

Ive done the defouler trick on my Monte, GTO & Sierra & it works

 

I replaced it with a Magna Flow high flow cat and the defouler sounds the best. Where should i go to find it and does it have to fit my year and make or are they universal?