For the o2 sensor plug you also need this bracket
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Euro header install - euro O2 sensor routing?
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Ok I was concerned about rooting the pre cats the old way and keeping them off the headers (keep them away from the heat). But I’ll take a look.
Why do I need that bracket exactly? Just to hold the location of the wire? Where did you get it?Last edited by Maxhouse97; 08-23-2025, 04:18 AM.‘04 M3
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Found this post that explains a lot, appliance searched better.
I've read that switching to euro cats requires lengthening the secondary O2 sensor wires in order for them to reach the section 1, is that right? (that is, if you want to run secondary O2s) How about the EGT sensor, does that reach without modification or does that require lengthening as well? I probably won't bother with the
‘04 M3
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I poked a few holes in the heatsheild and ran heat resistant zip ties through to secure the wiring right above the sensors. I also used those U shaped rubber coated "hangers" that you can find at the hardware store, 2 of them found spots right where a factory bolt was present and holds the wire in just the right area. Not OEM, but works and looks great.Originally posted by Maxhouse97 View PostOk I was concerned about rooting the pre cats the old way and keeping them off the headers (keep them away from the heat). But I’ll take a look.
Why do I need that bracket exactly? Just to hold the location of the wire? Where did you get it?2004 Silbergrau Metallic 6MT
Karbonius/OEM Snorkel/Flap/HTE Tuned
Ssv1/Catted Sec. 1/SS 2.5" Sec. 2/SCZA
OE CSL Bootlid/AS SSK/BC Coils/4.10 Gears/ Sportline 8S Wheels/Cobra Nogaros
RACP Plates/Vincebar/CMP/Turner RTAB/Beisan
2006 M6 Black Saphire SMG
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On the heat shield above the headers, there are two metal clips that hold the pre-cat sensors away from the headers. The factory routing is the best for those two. For the post-cat and EGT, those are going down the driver's side of the transmission along the transmission tunnel where there are plastic clips that hold the gear position and trans temp sensor wires. Once the wires get to the transmission tunnel heat shield, they can be clipped to the transmission tunnel heat sheild using those same clips found on the header heat shield - probably need 4 of the metal clips.Originally posted by Maxhouse97 View PostOk I was concerned about rooting the pre cats the old way and keeping them off the headers (keep them away from the heat). But I’ll take a look.
Why do I need that bracket exactly? Just to hold the location of the wire? Where did you get it?

This method of using the clips looks factory-ish and the O2 sensors will be easily removable when it comes time to remove the exhaust.
If the plastic bracket on the Euro cars that holds the post-cat sensors was readily available, that would be the best option, but one or two of the metal clips (pictured above) is still required to clip and hold the post-O2 sensor wires above the cats.Last edited by Slideways; 08-23-2025, 06:50 AM.
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The bracket can be ordered from bmw. It’s so your o2 sensor connector is secured properly and also prevents it from being that and coming loose.Originally posted by Maxhouse97 View PostOk I was concerned about rooting the pre cats the old way and keeping them off the headers (keep them away from the heat). But I’ll take a look.
Why do I need that bracket exactly? Just to hold the location of the wire? Where did you get it?
The pre cat routing is basically the same as all us models. You just have to use the before mentioned clips and heat won’t be a problem at all
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