Constant P0420/P0430

[GhostOutlaw]

I've replaced both cats, all the sensors, I use top tier fuel, there's a catch can in place and I STILL ****ING THROW P0420/P0430 randomly. I clear it and it usually goes away until the next fill up.

I'm at the point I'm thinking a cat delete, both myself and my mechanic don't know what to do.

Anyone else have this?

[JB'sZL1]

Headers? If so, it's in the tune. What brand cats and sensors? Those can throw codes as well.

[GhostOutlaw]

OEM replacements. Stock headers.

[fhrex]

mine threw a P0420 about 8 months ago, cleared code, never came back....knock on wood...

['10CamaroDude]

Same here, I had to add extenders, and one spacer:




I had P0430, continually, it was because #1, it was a Bosch sensor, and you have
to use FACTORY ones. #2, the dopes drilled holes in the tip of the sensor. These
idiots had the car for TEN weeks. I fixed in in a matter of minutes, once I put the
OE sensor back in, what they could not do in 2.5 months!


So, I had to go back to factory on that side, used an extender, then added an anti-fouler, and
it went away. I then replaced the accelerator pedal assembly, and then got the P0420 and I
wasn't with two anti-foulers on it. So I added the extender, and one anti-fouler to that, and
everything has been good since. These cars are very sensitive...

P0430 and P0420 means the primary cats are flowing too fast. Usually with
replacing them with non OEM cats, they're more hi-flow.

Nothing monitors the secondary cats, so mine are out. However, removing them may
also increase flow, thus the codes.

Go to your local parts store and add ONE of these to each side:

Wait and see if the codes come back. IF they do, put ANOTHER one
on the effected side(s).

I ended up having to go three lengths deep on each side, one long extender,
and one anti-fouler.

[GhostOutlaw]

So, my issue with using the foulers is that it doesn't fix the actual cause of the problem. It just makes it so that the sensors can't detect the flow as well.

I'd rather fix the actual problem.

['10CamaroDude]

Originally Posted by GhostOutlaw

So, my issue with using the foulers is that it doesn't fix the actual cause of the problem. It just makes it so that the sensors can't detect the flow as well.

I'd rather fix the actual problem.

Then you will be spending $300+ per side for factory down-pipes, which
has the primary and secondary cats -vs- 5% of that on spacers.

There is no REAL problem, it means the primary cats are flowing too fast.
That would be the SAME as if you bought hi-flow cats to replace your factory
ones. You'd still need the spacers on each side, because the car thinks
the primary cats are bad, and allowing too much flow, but you have new
hi-flows on, like MINE, well, now minus the secondary cats. I am also
averaging 25.5 MPG without the secondaries.

As long as you do not have any UPSTREAM codes, you're fine. That will
effect how the car runs. You can run with P0430/20 codes and it will
run just fine.

The point also, is this shows just how much a a fraud Emissions testing
actually is. If you can gut your cats, and put spacers on the downstream
sensors, for no CEL, it's just a racket.

[GhostOutlaw]

Originally Posted by '10CamaroDude

Then you will be spending $300+ per side for factory down-pipes, which
has the primary and secondary cats -vs- 5% of that on spacers.

There is no REAL problem, it means the primary cats are flowing too fast.
That would be the SAME as if you bought hi-flow cats to replace your factory
ones. You'd still need the spacers on each side, because the car thinks
the primary cats are bad, and allowing too much flow, but you have new
hi-flows on, like MINE, well, now minus the secondary cats. I am also
averaging 25.5 MPG without the secondaries.

As long as you do not have any UPSTREAM codes, you're fine. That will
effect how the car runs. You can run with P0430/20 codes and it will
run just fine.

The point also, is this shows just how much a a fraud Emissions testing
actually is. If you can gut your cats, and put spacers on the downstream
sensors, for no CEL, it's just a racket.

Delete the cats! Got it!

[camguynj]

Originally Posted by '10CamaroDude

Then you will be spending $300+ per side for factory down-pipes, which
has the primary and secondary cats -vs- 5% of that on spacers.

There is no REAL problem, it means the primary cats are flowing too fast.
That would be the SAME as if you bought hi-flow cats to replace your factory
ones. You'd still need the spacers on each side, because the car thinks
the primary cats are bad, and allowing too much flow, but you have new
hi-flows on, like MINE, well, now minus the secondary cats. I am also
averaging 25.5 MPG without the secondaries.

As long as you do not have any UPSTREAM codes, you're fine. That will
effect how the car runs. You can run with P0430/20 codes and it will
run just fine.

The point also, is this shows just how much a a fraud Emissions testing
actually is. If you can gut your cats, and put spacers on the downstream
sensors, for no CEL, it's just a racket.

What he said! If you don't want to put on extenders then pay thru your ass for nothing or ... sell the car and drive a Prius. I’m just being a wize ass. Seriously those codes just mean the cats are functioning/filtering emissions at a variance to specs. They is nothing wrong with your engine.