Had the p0420 code thrown. Reason was that Oxygen sensor 1 pre and oxygen sensor 2 post catalytic converter read too similar readings. I believe my catalytic converter is faulty but to save the cost of replacement I trialled an oxygen sensor fouler which you can get on ebay for $10. After running many miles and cycles my code has permanently been solved. Oxygen sensor bank 1 Pre cat reads correctly and the post cat o2 sensor only slightly fluctuates on voltage between 0 and 1 volt. The read out after this mod is an average 0.7v with slight fluctuations. This is the VW solution for this problem but im not sure which oxygen sensor the vortec 3.7 adjusts fuel trim between rich and lean and if this mod is causing the motor to run unhealthy in either direction.

 

A plugged cat can cause serious problems. Sounds like a bandaid on a heart attact. Makes you feel good to a moment until your heart takes a dive.

 

"A plugged cat can cause serious problems. Sounds like a bandaid on a heart attact."
I agree with Tainter on this one, however, this fouler works great on an empty cat. With emission testing being done through the OBD II diagnostic port, many performance mods use the fouler. It eliminates the need for a cat unless there is a tailpipe test. It also works on a stock motor. Not sure who came up with this but it works.

 

What tests can I perform to check if it is plugged?

 

A pressure test is the most effective way to test your cat. Remove the upstream O2, and use an adapter with a gauge. I think anything over 3psi at 2000rpm is a fail. I'm not positive on those numbers.

 

After researching this further I found that Catalytic converters can suffer from either being plugged or losing their efficiency.

I did an exhaust back pressure test on mine and its pressure was 0psi with a fluctuation of 0.5psi throughout all rev ranges. This indicates its not plugged and operating fine. Its just lost its efficiency to reduce NOx.

So good to know TAINTER was wrong on this one but has been a very valuable lesson to learn anyway.

 

Where was TAINTER wrong? A plugged cat CAN cause serious problems and the bandaid fix should not be implemented before finding out the real issue.

 

TAINTER was not wrong. He was concerned about how not doing the proper repairs can cause plenty of grief and coin down the road. It pays to do your homework before doing bandaid repairs. Shorty now knows that his cat is free flowing at this point in time. I would also recommend replacing the cat or gutting it. Do your homework Shorty. Make sure your O2 fouler works with an empty cat. Also check with local laws to make sure that it is legal.