Would I get a check engine light if I switched my cats?

[Matt.Weaves]

Hi,
Just a quick question... If I decided to switch out my catalytic converter with a magnaflow cat would i get a check engine light, and also would i still pass emissions?
Thanks

[Mach540]

Maybe.
If installed properly, no.

[ColtonBH]

Maybe, and maybe
That helpful?

You theoretically shouldn't, but if it does you can use spacers to pull the O2s out of the airstream to trick it. If your state has an emissions test with a sniffer, I would not mess with it

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[JimLev]

I removed the front CAT's when I installed headers, I'm only using the 2 main CAT's now, no codes here.

[6spd540]

I live in CA and have been running Magnaflow cats for my past 4 smog checks and never got a CEL light related to cats since changing them(I do have a M62 engine so that should be noted).



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[Matt.Weaves]

- - - Updated - - -

is that the only exhaust mod you have done??

I live in CA and have been running Magnaflow cats for my past 4 smog checks and never got a CEL light related to cats since changing them(I do have a M62 engine so that should be noted).



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[6spd540]

- - - Updated - - -

is that the only exhaust mod you have done??

No, I have all stock resonators removed, and x-piped dual exhaust. Basically everything from Cats and back has been changed.

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[geargrinder]

+1 to above. If the cat is a good one then shouldn't be an issue. These cars aren't tricky w/ aftermarket cats as far as what I've seen from so many guys going aftermarket cats. Different story with other BMW motors (I6's seem to be more 'cat finicky') but the 540 DME seems to be fairly 'reasonable' about the parameters of cat operation and accepting an aftermarket swap.

[6spd540]

I'd also like to mention that at the time that I decided to go with the Magna flow cats, some others that had ran them said they were only good for 2 smog checks. While I've made it way past that it's getting closer to not passing and it may help that mine is a M62 engine and if it was a M62tu it wouldn't (I believe the specs are tighter on the newer models-since they have more emissions control stuff).

BTW I only went with the Magna flows because my stock ones were clogged, new ones were way too expensive, didn't feel like taking a gamble with used ones and even with a CARB stamp the Magna flows price was pretty cheap that I wouldn't mind having to change every 4yr (as for the only good for 2 smog checks)

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[Matt.Weaves]

Can I hear it? I want to get an understanding of how it sounds. Also do you have quad tips?

No, I have all stock resonators removed, and x-piped dual exhaust. Basically everything from Cats and back has been changed.

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[6spd540]

Can I hear it? I want to get an understanding of how it sounds. Also do you have quad tips?

I don't have a recording but I guess I could make one. It has quad 3'' DTM style tips (next time I'll use a different style, I may just change them soon since they're starting to look bad I don't think they'll polish out easily). It's bit quieter at idle than I expected/wanted but much louder when rev'd than I wanted, and at cruising speeds it's not bad inside the cabin (unless you want a quiet car). This set up is a bit raspy when rev'd and sometimes pops on off throttle.

I build the system out of 2.5'' stainless, all mandrel bends TIG'd butt welds.

If/when I get my touring I'll be doing the system a bit different, instead of 2 dual tip mufflers I'll only use a single muffler were my x-pipe is (Magna flow makes one with an x-pipe build inside it I'll likely use if it will fit). I'll be doing this so I can still carry a full size spare for road trips, plus it should end up being a little quieter.

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[impster]

When I had my 540i, replacement Magnaflows triggered the CEL. Added spacers to the O2 sensors and it didn't help (all 4 O2 sensors were new).

[Matt.Weaves]

Yea mine is a single tip. Can you link where you got your Magnaflow cats?

I don't have a recording but I guess I could make one. It has quad 3'' DTM style tips (next time I'll use a different style, I may just change them soon since they're starting to look bad I don't think they'll polish out easily). It's bit quieter at idle than I expected/wanted but much louder when rev'd than I wanted, and at cruising speeds it's not bad inside the cabin (unless you want a quiet car). This set up is a bit raspy when rev'd and sometimes pops on off throttle.

I build the system out of 2.5'' stainless, all mandrel bends TIG'd butt welds.

If/when I get my touring I'll be doing the system a bit different, instead of 2 dual tip mufflers I'll only use a single muffler were my x-pipe is (Magna flow makes one with an x-pipe build inside it I'll likely use if it will fit). I'll be doing this so I can still carry a full size spare for road trips, plus it should end up being a little quieter.

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[6spd540]

Yea mine is a single tip. Can you link where you got your Magnaflow cats?

It was a decade ago, I really can't remember. It was likely which ever reputable retailer that had the best price and quickest shipping, I do remember I got the SS tubing, flanges and mandrels from Summit, maybe the cats also.

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[Matt.Weaves]

Ok please let me know when or if you will send me a video of the exhaust. Its the make it or break it senario. Also if I only changed the cats wouldn't that make the exhaust louder or would i have to do something with the resonators also? I currently have a muffler delete, but want it louder and more raspy.

It was a decade ago, I really can't remember. It was likely which ever reputable retailer that had the best price and quickest shipping, I do remember I got the SS tubing, flanges and mandrels from Summit, maybe the cats also.

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[6spd540]

I recorded quick audio file where I started car and rev'd with door open for an idea of how it sounds from out side then closed door and rev'd again.

I'm just not sure the best way to share it with you. The site and YouTube won't let me upload an audio only file.

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[Matt.Weaves]

Dm it on insta @Project_e39_540i

I recorded quick audio file where I started car and rev'd with door open for an idea of how it sounds from out side then closed door and rev'd again.

I'm just not sure the best way to share it with you. The site and YouTube won't let me upload an audio only file.

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[Matt.Weaves]

Do you have instagram?

I recorded quick audio file where I started car and rev'd with door open for an idea of how it sounds from out side then closed door and rev'd again.

I'm just not sure the best way to share it with you. The site and YouTube won't let me upload an audio only file.

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[6spd540]

Do you have instagram?

I already sent it to you on intagram a few hours ago.

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[Matt.Weaves]

My New plan is to do a resonator delete and get high flow mag cats. Does anyone know where I could get these? Thanks