x-pipe p0420 and p0430

[midnightrumbler]

I just put a bassani 2.5" xpipe with high flow cats on my 2000 mustang gt and switched my functioning o2 sensors to this system and now I am getting the above mentioned codes.

I know what the codes indicate but why would I now be getting them?

The car does smell like a carbed version and I really have nothing else done to show these codes.

Thanks in advance

[Ponyryd]

Is it a new pipe? Likely the cats aren't cleaning the exhaust much if at all.

[Spock]

Because those "High Flow Cats" aren't doing anything & your cat monitors are telling you that.

[midnightrumbler]

Suppose the MIL eliminators will remove the light but not really fix the problem?

I have used high flow cats prior on various vehicles without incident. Does this happen with most if not all aftermarket h/x pipes?

[Ponyryd]

Ya, mil elims should solve it. Aftermarket pipes with good cats should not throw a code.

[midnightrumbler]

Perhaps the a series of o2s could be bad on either bank tossing the code as it appears the car is dumping fuel smelling like a carb'd version.

I'll hook up a real time obd reader and see what the o2s are running

[ZR]

Common when running an aftermarket pipe n cats.
MIL's or tune for it.

[midnightrumbler]

Can you recommend a good tune/tuner either programmable handheld or at a service facility?

Motor is stock with CAI, 2.5" xpipe, under drive pulleys, ac delete

[Speedtospare]

Was the exhaust you installed new? I have the cheapie vibrant High flow mini cats in my BBK x-pipe and it has no smell at all. We put brand new Long tubes with cats on Kyles car and untuned it still doesnt smell like a car with no cats,

IMO I'm going to say broken cat.

[Ponyryd]

Perhaps the a series of o2s could be bad on either bank tossing the code as it appears the car is dumping fuel smelling like a carb'd version.

I'll hook up a real time obd reader and see what the o2s are running

If it smells it's very likely that the cats are bad, a bad downstream 02 on a 2000 won't cause a big difference in fuel delivery. Not to mention you had no issue before the cat swap, two bad sensors after a simple pipe swap is very unlikely.

[midnightrumbler]

The system was not brand new

[ZR]

ding ding, now the suspected cat(s) problem makes more sense.

[Speedtospare]

Stick something down there and see if there still in one piece.