O2 Sensor extension wire for catless DP CEL fix

[rockyfeller]

I'm planning to install catless downpipes but I'm one of the few not interested in doing a tune because I don't want to void my extended warranty. The exhaust system isn't covered under warranty so that doesn't matter. But a tune will be detectable, even if removed, and will kill my DME, engine, turbos etc etc. warranty. I'm also doing this purely for the sound. I'm fully aware of the power gain potential of a tune but I'm not interested. Happy with the stock power output.

So what I'm concerned of is the CEL and want to install a O2 emulator to eliminate it. There is some mention of "A seven four" emulator out here (can't type out the full name here, forum blocks it) and another by Magnum Tuning some with success, others without. Can anyone chime in on their experience with it?

But the main purpose of this thread was to ask if anyone knows where to source the post-cat (downstream) O2 sensor harness? I don't want to hack up the stock wiring of the O2 sensor and I'd rather devise a plug in harness solution so I can splice the O2 emulator into a separate harness and make it plug n play and reversible. If I'm not wrong the N63 shares the same O2 sensor has the S63 engine. I searched everywhere for an "O2 sensor extension wire", which is available for many cars out there and would definitely be perfect for my needs but couldn't find one.

Any advice guys?

[rockyfeller]

After digging around a bit I'm getting closer to a solution. For one thing I found that our downstream O2 sensors are not only cross compatible with the N63 engine, but many other cars including MB! Weird. Can anyone confirm on any of these models?

If that's the case I don't have the pay the "S63" tax and I'll be able to use a cheap set of generic O2 sensors as donors for the harness. I'm sure the O2 sensor itself would be substandard for our ultra-sensitive engine DMEs, but the sensor itself is going to be chopped off and chucked out anyways.

Also I got an email from A74 that they are still "beta testing" on the S63. Meaning it isn't ready for prime time yet. After seeing so many old threads of N55 and S63 guys trying to tinker with it, its safe to say that it's a no-go. Apparently they've been "beta testing" for years at this point, so I'm not holding my breath. Lol. There's no adjustment for the voltage on this unit and there's no return policy. So, yeah, no thanks.

I'm going to go with the Magnum Tuning unit. It's cheaper, voltage adjustable, has a return policy and a 10yr warranty. There's an N55 member who did a full writeup showing it worked out for him.
https://f10.5post.com/forums/showthread.php?t=1609409#

So I'm going in on this, let's see what happens. I'll update you guys and let you know the results.

[rockyfeller]

Alright so it's confirmed. The harness works! No need to get OEM or S63 spec O2 sensors as donors. Crazy to think a MB C220 uses a similar plug, yet most of BMW's own line don't cross match.

Of course the quality is not that great (as expected) but it gets the job done. There is one issue, the yellow rubber seal is a bit too thick. This prevents the harness plug to seat fully and fit perfectly. Once you remove the yellow band it fits and locks in place. But of course you lose water protection. Hi temp electrical tape should fix that.

[rockyfeller]

Would anyone happen to know what the specific voltage should be for the the downstream O2 sensor (post-cat) on the stock setup? I've googled everywhere, no answer anywhere.