[Wires]

Originally Posted by ScubaSteve

I'm confused a little, I have a 2013 335 xdrive which is n55 and have the p0420 code on. I've had a catless dp and jb4 installed for years and no issue or cel of any kind and then the light came on about 1 month ago. I had a bit of a rattle going on and when I finally was able to get under the car I noticed that the exhaust hanger mount in the mid section right after the flex part had snapped off (car is quite low on H&R springs). My first task is to fix the hanger mount so the exhaust is not moving around anymore. I've read that the 0420 code could also be cause by an exhaust leak, and wondering if possibly with the exhaust being slightly lose like that for a while is what is possibly causing the light to come on if indeed there is a small leak somewhere. I don't really have a good garage or place to work on my car anymore, besides taking it to a muffler shop if there is a leak I would assume having it welded would be the best and only option?

Very possible. The O2 sensor is measuring O2 in the exhaust (raw fuel has high oxygen content). If you are getting fresh air sucked back in, it's possible to get a false positive O2 CEL.

The way it's configured is there is a wideband O2 that is pre-cat to run the fueling for the engine. And then they run a narrow band O2 post cat to check if the emissions are working as expected (since if it's fueling properly, and the cat is scrubbing the exhaust, it should all be in check).

[cevmesbag]

What size should I get for VRSF Catless Downpipe?

[Wires]

Originally Posted by cevmesbag

What size should I get for VRSF Catless Downpipe?

They only have one option don't they? Just a catted or catless version for the B58?

[RawDog]

After reading through this, looks like a spacer is a 50/50 shot of not throwing a CEL?

Best option being buy DS1 or AA downpipe without the hastle?

[tarekelsakka]

Originally Posted by RawDog

After reading through this, looks like a spacer is a 50/50 shot of not throwing a CEL?

Best option being buy DS1 or AA downpipe without the hastle?

I'm in the same boat right now. I am considering the VRSF because it's cheap enough and within my budget but I honestly don't want to deal with CEL or spending over $500 USD for a bootmod3 license even though I don't even want to tune/remap. I think I'll give the o2 spacer a shot, but if you can afford it, a catted downpipe is quite hassle-free but much more expensive. ArmyTrix sells some of the best high-flow catted DPs out there, and make sure you get it ceramic coated if you live in a hot area.

[blacksapphire440i]

Originally Posted by tarekelsakka

I'm in the same boat right now. I am considering the VRSF because it's cheap enough and within my budget but I honestly don't want to deal with CEL or spending over $500 USD for a bootmod3 license even though I don't even want to tune/remap. I think I'll give the o2 spacer a shot, but if you can afford it, a catted downpipe is quite hassle-free but much more expensive. ArmyTrix sells some of the best high-flow catted DPs out there, and make sure you get it ceramic coated if you live in a hot area.

I would just live with the CEL and have a scan tool on stand by just in case your car does have any issues. Just my 2 cents tho

[Info@mad-us.com]

Originally Posted by blacksapphire440i

I would just live with the CEL and have a scan tool on stand by just in case your car does have any issues. Just my 2 cents tho

The Budget combo If you don't have a tune.

Scanner / code deleter. https://www.amazon.com/Autel-MaxiSca...ps%2C89&sr=8-3


Downpipe- https://mad-us.com/mad-b58-downpipe-...chassis-supra/

[RawDog]

Originally Posted by tarekelsakka

I'm in the same boat right now. I am considering the VRSF because it's cheap enough and within my budget but I honestly don't want to deal with CEL or spending over $500 USD for a bootmod3 license even though I don't even want to tune/remap. I think I'll give the o2 spacer a shot, but if you can afford it, a catted downpipe is quite hassle-free but much more expensive. ArmyTrix sells some of the best high-flow catted DPs out there, and make sure you get it ceramic coated if you live in a hot area.

the AA is the only CEL guarantee pipe though. I think I saw some of the DS1's popping cel lights on a post

[Wires]

Originally Posted by blacksapphire440i

I would just live with the CEL and have a scan tool on stand by just in case your car does have any issues. Just my 2 cents tho

This also masks any other major CEL's that get thrown. Basically you are saying "put a piece of electrical tape over the check engine light".

[BeFitty8_F32]

The biggest lesson I have learned from owning any car, is that sometimes it sucks and hurts the wallet. Doing the correct thing with proper parts is always the way to go.

Sometimes you dont have the money, I get it. But if you do, dont be cheap. Unless its a "beater" and you dont care.

Good luck! I need some too with my recent purchase.

[Wires]

Originally Posted by BeFitty8_F32

The biggest lesson I have learned from owning any car, is that sometimes it sucks and hurts the wallet. Doing the correct thing with proper parts is always the way to go.

Sometimes you dont have the money, I get it. But if you do, dont be cheap. Unless its a "beater" and you dont care.

Good luck! I need some too with my recent purchase.

My buddy used to say "You got to pay to play!"

[blacksapphire440i]

Originally Posted by Wires

This also masks any other major CEL's that get thrown. Basically you are saying "put a piece of electrical tape over the check engine light".

Yea but that is why you would have a scan tool on standby to check for any other codes. for an example a CEL wouldnt pop up if your injectors were stuck/leaking. Which brings u back to the question of why you want a downpipe and not a tune to compliment it. cant have both worlds at the same time with different objectives. plus o2 spacers potentially cut off data being tracked by the o2 sensors

[Wires]

Originally Posted by blacksapphire440i

Yea but that is why you would have a scan tool on standby to check for any other codes. for an example a CEL wouldnt pop up if your injectors were stuck/leaking. Which brings u back to the question of why you want a downpipe and not a tune to compliment it. cant have both worlds at the same time with different objectives. plus o2 spacers potentially cut off data being tracked by the o2 sensors

How would you know there were other CEL's if the light is on all the time? Not like you would have your scan tool on all the time continuously monitoring it.

The spacer doesn't change any data/operation. Lower O2 sensor is there just to trigger the CEL if the O2 drop across the cat makes no sense (emissions are not working properly). If you are changing the DP, then you really don't care about that CEL code.

Won't disagree with your point about getting the DP without the tune is a bit of a waste though.

[Info@mad-us.com]

Originally Posted by Wires

How would you know there were other CEL's if the light is on all the time? Not like you would have your scan tool on all the time continuously monitoring it.

The spacer doesn't change any data/operation. Lower O2 sensor is there just to trigger the CEL if the O2 drop across the cat makes no sense (emissions are not working properly). If you are changing the DP, then you really don't care about that CEL code.

Won't disagree with your point about getting the DP without the tune is a bit of a waste though.

Think the idea would be to clear the o2 code once it pops up and check the read before clearing.

Manual code clearing instead auto code clearing like the jb4 used to do.

[Wires]

Originally Posted by Info@mad-us.com

Think the idea would be to clear the o2 code once it pops up and check the read before clearing.

Manual code clearing instead auto code clearing like the jb4 used to do.

Yes, I get that. But if you have a DP that throws code, then 5 minutes into a drive, it will pop back up again. That was the case with my catted VRSF. So "ignoring" really isn't an option since it's masking all the other codes that may be critical to the car.

[blacksapphire440i]

Originally Posted by Wires

How would you know there were other CEL's if the light is on all the time? Not like you would have your scan tool on all the time continuously monitoring it.

The spacer doesn't change any data/operation. Lower O2 sensor is there just to trigger the CEL if the O2 drop across the cat makes no sense (emissions are not working properly). If you are changing the DP, then you really don't care about that CEL code.

Won't disagree with your point about getting the DP without the tune is a bit of a waste though.

I mean I feel like the O2 sensors do something. One of my friends has a 2021 M340i and he put a vrsf catless downpipe on the car and after a couple months, car felt slower and it burnt through a crap ton of oil to where the car notified us when we were at a mall. Car also started spitting out a ton of fumes and was fixed whenever the o2 sensors were fixed along with the stock downpipe put back on

[Info@mad-us.com]

Originally Posted by blacksapphire440i

I mean I feel like the O2 sensors do something. One of my friends has a 2021 M340i and he put a vrsf catless downpipe on the car and after a couple months, car felt slower and it burnt through a crap ton of oil to where the car notified us when we were at a mall. Car also started spitting out a ton of fumes and was fixed whenever the o2 sensors were fixed along with the stock downpipe put back on

The primary o2's are 100% needed as they help with the tuning of the car. Secondary's can be tuned out.

Flash tune makes this entire process much easier if you are out of warranty.

[Wires]

What he said. One above the cat is used for fuel adjustments. One after the cat is just there to toss the CEL if the DME is seeing too much O2 (unburnt fuel) in the exhaust after the cat. Not needed for operation, just used to ensure the emissions are operating to spec. Once you put in a high flow cat or catless DP, emissions are not in your area of concerns, so it can be tuned out.