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      02-20-2023, 10:50 PM   #1
GrayZ4MCoupe
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Exclamation Modded S54 E86 Z4 M Coupe - Codes 29F4 and 29F5 - Catalytic Converter Conversion ??

Hi everyone, I have a "Service Engine Soon" light on my dash and was looking for help on these codes that I pulled:

0029F4 - Digital Motor Electronics (DME), catalytic converter conversion
0029F5 - Digital Motor Electronics (DME), catalytic converter conversion 2


The car has a Schrick 288/280 cam, Eventuri intake, Supersprint headers, & Rpi Exhaust for the motor mods.

Bad O2 sensors? Bad cats? Bad something else? Haven't been able to find much about these exact codes for the S54 online.

Also, not sure about the alternator code 2E97, but that could be because I didn't have the car engine running and only on ignition position 2 during the reading of the codes.

Thanks in advance!
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      02-21-2023, 05:17 AM   #2
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Do you have the stock cats in the section 1? Did you relocate the post cat o2 sensors after the cats in the section one after header install?

Those codes mean your cats are not working fine. I have them, but my cats are aftermarket and not as effective as OE.
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      02-21-2023, 09:06 AM   #3
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Quote:
Originally Posted by maupineda View Post
Do you have the stock cats in the section 1? Did you relocate the post cat o2 sensors after the cats in the section one after header install?

Those codes mean your cats are not working fine. I have them, but my cats are aftermarket and not as effective as OE.
I'm not sure, I'll have to get under the car and take a look. This is a "new to me" car, so I'm still exploring the car. Do the stock cats have BMW markings on them or anything else to validate that they're OEM vs high-flow?
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      02-21-2023, 09:53 AM   #4
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There are 4 cats in the stock setup - 2 in the headers and 2 in section 1 (as indicated by maupineda). The original locations of the O2 sensors are in the headers. Since you've got catless headers, the O2s should have been relocated to the section 1 cats. So make sure you first have OE cats in section 1, then look and see if the O2s are there.
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      03-13-2023, 03:07 PM   #5
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Quote:
Originally Posted by maupineda View Post
Do you have the stock cats in the section 1? Did you relocate the post cat o2 sensors after the cats in the section one after header install?

Those codes mean your cats are not working fine. I have them, but my cats are aftermarket and not as effective as OE.
Finally got a chance to get some pictures/videos of the bottom of the car. Hopefully, this can shed some light on what I have and what I do not since I'm not as familiar with the stock set up.

Youtube video of the underneath of my car showing the O2 sensor locations: https://youtube.com/shorts/VWJaXc6EL8M?feature=share
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      03-13-2023, 07:24 PM   #6
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Everything is working fine as expected. You’ve got codes because you’re running catless supersprint headers. In the absence of primary cats, your o2 sensors think the cats are not functioning when you simply don’t have any.

Others here have avoided codes by relocating the sensors to the secondary cats. You can hack your existing and weld in o2 bungs or buying a set of secondaries that come with bungs.

Good thread with pictures:
https://www.zpost.com/forums/showthread.php?t=521081
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Last edited by 3002 tii; 03-16-2023 at 01:01 PM..
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      03-13-2023, 07:37 PM   #7
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is very clear your O2 post-cat sensors are placed before the cats, and not after, so the downstream sensors see the same gases as the upstream ones; the car's ECU interprets this as faulty cats.

you need to move the 02 sensors after the cats, this means you need to modify your cats to add the bungs and install the downstream sensors after the cats.

also, your two downstream sensors are on the same header, it should be one per bank.
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      03-16-2023, 09:42 AM   #8
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Quote:
Originally Posted by maupineda View Post
is very clear your O2 post-cat sensors are placed before the cats, and not after, so the downstream sensors see the same gases as the upstream ones; the car's ECU interprets this as faulty cats.

you need to move the 02 sensors after the cats, this means you need to modify your cats to add the bungs and install the downstream sensors after the cats.

also, your two downstream sensors are on the same header, it should be one per bank.
Would another solution possibly be to get a tune that removes the secondary O2 sensors?
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      03-16-2023, 01:36 PM   #9
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That is another option, but then the car wont pass emissions if your state has smog checks
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      04-11-2023, 12:08 AM   #10
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Quote:
Originally Posted by GrayZ4MCoupe View Post
Would another solution possibly be to get a tune that removes the secondary O2 sensors?
If the o2’s are disabled, it will show they are not functioning when they check emissions readiness. Most states allow a max of 1 “not ready” OBD readiness monitor but that 1 is typically reserved for catalyst (since you’re catless). The oxygen sensor may put you over.

You should google area 74 o2 simulators. I used those on my n52 coupe and was able to pass emissions. It would occasionally trip a CEL when I did WOT runs but it did the trick for emissions.
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