p0420 02 sensor replacement?

[matt3989]

well my car threw a p0420 yestarday, thats a Catalyst System Efficiency Below Threshold (Bank 1), what are the causes? do you think it would be something wrong with the cat or with the sensor?

[97rs4life]

Re: p0420 02 sensor replacement?

your cat has most likely taken a poop

[matt3989]

Re: p0420 02 sensor replacement?

I replaced the cat last year when I put my new exhuast on

[97rs4life]

Re: p0420 02 sensor replacement?

I replaced the cat last year when I put my new exhuast on

replaced it with what kind, and size?

[BLLDOGG]

Re: p0420 02 sensor replacement?

hey goober, what kind of car do you have.

he replaced it with a magnaflow highflow cat. probably need an 02 sim or a new one if you have one

[matt3989]

Re: p0420 02 sensor replacement?

I have a '99 camaro

I replaced it with a 94100 series high flow from magnaflow, it says it will support up to 6.2L engines

the cat has less than 10K miles on it but the car has 87K, O2 sensors usually start to go at around 80,000 right? so should I just replace the post cat one?

[97rs4life]

Re: p0420 02 sensor replacement?

with hiflow cats you should have went with an 02 sim and ditched that sensor anyways. Or have the code tuned out with hptuners

[matt3989]

Re: p0420 02 sensor replacement?

I did seafoam about 2000 miles ago for the first time, I hear that can screw up your cat, is there anyway to tells if the cat is partially clogged or something

[BLLDOGG]

Re: p0420 02 sensor replacement?

it can also screw up you plugs and 02sensors.

Do a back pressure test or engine vacuum test

[Camarorulz]

Re: p0420 02 sensor replacement?

Just have it tuned out or get an 02 sim. That's what happens when you get a high flow cat or delete your cat. It throws P0420.