Euro O2 Sensor Harness - Connector Difference

[divedoc]

I'm in the process of installing the Euro O2 sensor harness for my Supersprint headers. I've run into an unexpected issue with connectors. See the attached photo; the new harness has a two-pin connector, where the old harness has a three-pin connector. You can see the male end of the connector in the background of the photo.

The old three-pin connector only has two wires going to it, and they're the same color wires as the one going into the new connector. I'm tempted to depin the connectors and swap them, but I just want to make sure that I'm not crazy. Has anyone dealt with this before? And, while I'm asking, what does that part of the harness do?

[nextelbuddy]

That's for the e-box fan

[divedoc]

Edit: I did a little more digging after learning that this is the connector for the e-box blower.

The current US part number for the blower includes a three-wire harness. It's also described as the correct blower for "SMG or hot climate" cars.

There's an alternative part number available for a blower in the Euro market with the two-wire harness. For whatever reason, this fan -- while physically located in the same place as the other blower motor -- has a physically different connector.

It looks like my options are to either find a harness adapter/pigtail, depin the connector as I'd originally planned, or find the Euro blower. Any experience or thoughts on this? (And yes...this is what I get for trying to be all cool and use a Euro harness for my headers.)

[Cubieman]

Just de-pin it man, you can always put it back how it was. I'm a sucker for keeping things as they are but that's my 2 cents.

[sapote]

I'm in the process of installing the Euro O2 sensor harness for my Supersprint headers. I've run into an unexpected issue with connectors. See the attached photo; the new harness has a two-pin connector, where the old harness has a three-pin connector. You can see the male end of the connector in the background of the photo.

I'm curious of why switching to the Euro O2 harness leads to the efan 2pin connector issue?

The purpose of the 3pin connector is that the DME monitors pin2, black/green wire, to detect if F3 (and the fan) working properly.

[divedoc]

I'm curious of why switching to the Euro O2 harness leads to the efan 2pin connector issue?

The purpose of the 3pin connector is that the DME monitors pin2, black/green wire, to detect if F3 (and the fan) working properly.

The Euro harness that I received only has a two-pin connector going to the e-box blower. I looked at the old harness, and while it has a three-pin connector, there are only two wires going to it (red with white stripe, brown with yellow stripe). So it looks like either way, there are only two wires going to it. Those pins are 1 and 3, or 3 and 1, I can't remember at the moment. Color-wise, those are the same two wires that go to the new harness's two-pin connector.

[bmwfnatic]

Checked a few euro cars here for the sake of science, fans are 3 wire. Harness side is 2 wires in a 3 wire connector (no middle pin).

[divedoc]

Checked a few euro cars here for the sake of science, fans are 3 wire. Harness side is 2 wires in a 3 wire connector (no middle pin).

Well now that's weird. I purchased part 12-51-7-835-524, which according to RealOEM is correct for the application. Looks like the part is current as of 2003, and it supersedes an older part number. FWIW my car is a July 2003 US spec manual coupe.

So what's going on here? Is this a case of manufacturing error, or something else? One other possibility: The new part is not a complete supercession, and the older harness is actually the one I need. But was there a change to the DME in that time period that would necessitate the change, or was it literally just this e-box fan connector? That older part number is shown as NLA.

[sapote]

Interesting as the document shows pin2 is used for monitoring:

[PSUEng]

Well now that's weird. I purchased part 12-51-7-835-524, which according to RealOEM is correct for the application. Looks like the part is current as of 2003, and it supersedes an older part number. FWIW my car is a July 2003 US spec manual coupe.

So what's going on here? Is this a case of manufacturing error, or something else? One other possibility: The new part is not a complete supercession, and the older harness is actually the one I need. But was there a change to the DME in that time period that would necessitate the change, or was it literally just this e-box fan connector? That older part number is shown as NLA.

I dug into this a few months ago and I think I reasoned to myself they "commonized" the fan as we say in the industry, and didn't change the harness.

[divedoc]

I dug into this a few months ago and I think I reasoned to myself they "commonized" the fan as we say in the industry, and didn't change the harness.

Interesting. So I got back onto RealOEM and browsed parts for a 7/2003 Euro E46 M3. I got two part numbers for the e-box blower.

-Part 12907570074 is listed as NLA, but the photo (found at bimmerworld) shows a two-pin connector.
-Part 12907571019 shows a three-pin connector and seems to be the currently available part. It's also labeled as the designated blower for auto/SMG/hot climate.

Of note, these are the same parts, part numbers, and applications that show up when I look up my own US spec car.

From all this, I surmise that the harness I received, for whatever reason, came with the two-pin connector intended for an e-box blower that is now NLA. But my car has a three-pin blower connector, whether it came that way or was replaced at some point. Seems like it would be safe to de-pin and replace the connector on my new harness with the three-pin connector that is compatible with my current (and any future) e-box blower. Sure hope I'm right...