catalytic converter Help

[gordon_gjs]

Can anyone help me? I currently have code P0420 on my 2003 Impala, it is a 3.8 liter v6. I have tried everything to clear the code. I have replaced both o2 sensors, new plugs and wires and a new catalytic converter last year. I had the catalytic converter replaced at a shop last year and was wondering if they could of put one too small? I will attach pictures of it and see if anybody here can tell me if the cat is too small. And would anyone know if the full bolt on magnaflow cat from autozone should solve the problem?








Thanks for any help I can get!!

[HeMi101]

Unless you buy an OEM Catalytic From GM (which you have to buy the whole Cat-back part for that, which is probably somewhere around 800 - 900$) Replacing the cat again will NOT fix the problem. The Rear O2 Sensor is very Picky, and even though the Catalytic is probably working fine, the rear 02 is reading values outside the very tight range it would expect from the OEM Cat.

You have 3 Options:
1) Live with the P0420
2) Buy an 02 Simulator (little chip that plugs into the Connector where the 02 sensor connects beside the cat)
3) Have the code deleted from your PCM.

[gordon_gjs]

Thanks for you're help Hemi101,
Would you know if deleting the code would let the car pass inspection?
And I saw the forum on 02 sim sensor's, is there one that you might know of that works well and would let the car pass inspection?

Thanks agian

[HeMi101]

In short, a Simluator Technically will get you failed on an inspection, BUT if you installed it really discretely, they probably won't notice it there. I'd suggest the one from www.ZZperformance.com .

You will pass No problem if you have the Code deleted, The PCM just won't know how to throw a code for "Catalytic Inefficiency", which is all the rear 02 Sensor does.

[gordon_gjs]

How much does it cost to delete the code form the PCM? And you I assume you would need an expensive tool to do this.
Thanks agian!

[HeMi101]

Originally Posted by gordon_gjs

How much does it cost to delete the code form the PCM? And you I assume you would need an expensive tool to do this.
Thanks agian!

You need someone with a Tuner, like a PowR Tuner or HPTuner. again Sim would be the cheapest route, but might not pass if they see it.

[gordon_gjs]

Thanks, I am ordering the part right now!