CEL fix for Catted Downpipes

[JDM BLKBMW]

I installed a very nice Downpipe, that appears as high a quality as any i have seen. But in 2 or 3 cruising driving cycles the P0420, catalyst inefficiency CEL comes on. I read alot of information about mini-cats, 02 spacers, 90 degrees spacer, 45 degrees spacers, Fab Speed, CST, Ebay versions, and the old Dorman 42002 spark plug anti foulers.

Most people that use these are using them on catless downpipes. But from what I have found, the 200 CELL catted downpipe, throws the code just like the catless downpipes. So the 200 Cell is not doing enough exhaust scrubbing to keep the CEL off. So most people tune them out via tuning. But on a locked/untuneable 2021 model, your choices are limited to only spacers, mini-cat etc.

I haven't found anyone that had complete success in getting the CEL to stay off with any apparatus other than tuning it out with the CATLESS pipes.

BUT, has anyone had success in getting a 200 Cell catted downpipe to quit throwing the CEL (without a tune)?

The solution might be different with the catted version, as to what may work. in this case, the exhaust is cleaned, but not clean enough, so maybe a spacer might work? Or a straight on mini-cat instead of a right ange one? Or mayber a 90 degree spacer without mini-cat

IF you put the o2 sensor too far out of the air stream it doesnt get hot enough, and gets a slow response signal. So those people got rid of the P0420 code, but got the slow response code and CEL.

Anyhow. Anybody have any definitive answers on what do do with an almost good enough catted downpipe?

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[Benjilis]

I installed a very nice Downpipe, that appears as high a quality as any i have seen. But in 2 or 3 cruising driving cycles the P0420, catalyst inefficiency CEL comes on. I read alot of information about mini-cats, 02 spacers, 90 degrees spacer, 45 degrees spacers, Fab Speed, CST, Ebay versions, and the old Dorman 42002 spark plug anti foulers.

Most people that use these are using them on catless downpipes. But from what I have found, the 200 CELL catted downpipe, throws the code just like the catless downpipes. So the 200 Cell is not doing enough exhaust scrubbing to keep the CEL off. So most people tune them out via tuning. But on a locked/untuneable 2021 model, your choices are limited to only spacers, mini-cat etc.

I haven't found anyone that had complete success in getting the CEL to stay off with any apparatus other than tuning it out with the CATLESS pipes.

BUT, has anyone had success in getting a 200 Cell catted downpipe to quit throwing the CEL (without a tune)?

The solution might be different with the catted version, as to what may work. in this case, the exhaust is cleaned, but not clean enough, so maybe a spacer might work? Or a straight on mini-cat instead of a right ange one? Or mayber a 90 degree spacer without mini-cat

IF you put the o2 sensor too far out of the air stream it doesnt get hot enough, and gets a slow response signal. So those people got rid of the P0420 code, but got the slow response code and CEL.

Anyhow. Anybody have any definitive answers on what do do with an almost good enough catted downpipe?

I was just told to fix this with a flash tune. So currently trying to gather enough info if BM3 or MHD is the way to go

 

[JDM BLKBMW]

That's what everyone mostly does. But those with late production 2021 models are untuneable currently with no solution in sight. For those unfortunate people that's not an option. So another solution must be found. Hoping someone has had luck.

 

[diablo2112]

 

[Supra Cat]

UN-interestingly, I used this method to fix the annoying shift light on my '87 Fiero GT, a million years ago.

 

[black_sedan]

My catted dp has a CEL fixed built in... I still got a code, in fact it kicked back a completely different code that the secondary o2 was reading too slow. Turned it off with a tune and it’s been fine.

 

[Benjilis]

I installed a very nice Downpipe, that appears as high a quality as any i have seen. But in 2 or 3 cruising driving cycles the P0420, catalyst inefficiency CEL comes on. I read alot of information about mini-cats, 02 spacers, 90 degrees spacer, 45 degrees spacers, Fab Speed, CST, Ebay versions, and the old Dorman 42002 spark plug anti foulers.

Most people that use these are using them on catless downpipes. But from what I have found, the 200 CELL catted downpipe, throws the code just like the catless downpipes. So the 200 Cell is not doing enough exhaust scrubbing to keep the CEL off. So most people tune them out via tuning. But on a locked/untuneable 2021 model, your choices are limited to only spacers, mini-cat etc.

I haven't found anyone that had complete success in getting the CEL to stay off with any apparatus other than tuning it out with the CATLESS pipes.

BUT, has anyone had success in getting a 200 Cell catted downpipe to quit throwing the CEL (without a tune)?

The solution might be different with the catted version, as to what may work. in this case, the exhaust is cleaned, but not clean enough, so maybe a spacer might work? Or a straight on mini-cat instead of a right ange one? Or mayber a 90 degree spacer without mini-cat

IF you put the o2 sensor too far out of the air stream it doesnt get hot enough, and gets a slow response signal. So those people got rid of the P0420 code, but got the slow response code and CEL.

Anyhow. Anybody have any definitive answers on what do do with an almost good enough catted downpipe?

I actually found out I can keep the JB4 and do a back end flash for $70. This will save money by not having an o2 spacer that won’t work. It will also had more power

 

[JDM BLKBMW]

My catted dp has a CEL fixed built in... I still got a code, in fact it kicked back a completely different code that the secondary o2 was reading too slow. Turned it off with a tune and it’s been fine.

Can you post a picture of the CEL fix that's built in to yours?

 

[Rocksandblues]

Can you post a picture of the CEL fix that's built in to yours?

He said it ultimately failed to keep light off. His code indicated that it was too far downstream and timed out.

 

[Supra Cat]

When you wrap your head around the need for emissions controls, instead of hating check engine lights, the answer is obvious. Some company needs to sell an emissions-effective catted downpipe. But it seems doubtful there's enough demand in North America for anyone to bring a DP like that to market, when all anyone seems to care about is 800 whp at the cheapest price.
"Don't be fooled into thinking a lower cell count automatically means a freer-flowing cat." Here: http://speed.academy/how-catalytic-converters-work/

 

[JDM BLKBMW]

He said it ultimately failed to keep light off. His code indicated that it was too far downstream and timed out.

I saw that. However I searched and found another thread where he couldn't see what the code was because it went off before he got to read it. That got me curious. Plus I'd like to see how MXP tries to handle the CEL code.

 

[black_sedan]

I saw that. However I searched and found another thread where he couldn't see what the code was because it went off before he got to read it. That got me curious. Plus I'd like to see how MXP tries to handle the CEL code.

only got a couple pics before installing the dp, not sure it will help much. The code I got was 139001 - lambda probe after catalyst delayed reaction

 

[black_sedan]

I actually found out I can keep the JB4 and do a back end flash for $70. This will save money by not having an o2 spacer that won’t work. It will also had more power

As I understand back-end flash still needs the Ecu to be flashed.

 

[Benjilis]

As I understand back-end flash still needs the Ecu to be flashed.

Correct. But it’s a cheaper shortcut right now than getting a o2 sensor thst won’t work.
I only plan to use ecutek when and if I upgrade the turbo

 

[black_sedan]

Correct. But it’s a cheaper shortcut right now than getting a o2 sensor thst won’t work.
I only plan to use ecutek when and if I upgrade the turbo

Unless you’re worried about warranty I would go straight to Ecutek, especially if you’re flashing the Ecu. Doesn’t make sense to run a piggyback and then flash an Ecu. Upgrade the turbo and you can just have a tuner send another map.

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