Euro header install - euro O2 sensor routing?

[Maxhouse97]

Reposting for more visibility. Anyone have a good diagram of how the euro sensors and harness are supposed to route? I purchase them used from BMwfnatic but not sure how they are supposed to be wired. This is what I have.

[Slideways]

Picture has euro sensors and the cable holder, but I don't see the full euro harness from the sensors to the DME.

Any one of the Redish underside restoration videos will show the placement of the cable holder under the car.

[Maxhouse97]

Ok thanks, I assumed there’s could plug into my existing harness but from your response my takeaway is no? Does that mean I have to splice into my existing harness? This was not clear to me, thanks.

[Phoenix///M3]

I have some good diagrams on my PC from my install. Will post tomorrow.


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[D-O]

As you know, the euro rear O2's are shorter. There is a lot of extra length in the US spec front harness if you unwrap it and re-route it down the drivers side of the trans, but still not enough to reach the rear euro O2's. The long US spec rear O2's will reach, but you wont really be able to use the bracket.

To use the bracket and the short rear O2's you will need the euro front harness, or you will need to cut and extend your existing harness. Heinzbohmer's build thread has a bunch of posts detailing unwrapping and re-routing the US spec harness.

[Maxhouse97]

Ok thanks - appreciate the specific thread recommendation. Are there any downsides to routing the wires on the driver side? This is my track car, so I need to ensure that nothing gets melted hot running.

[Slideways]

Ok thanks - appreciate the specific thread recommendation. Are there any downsides to routing the wires on the driver side? This is my track car, so I need to ensure that nothing gets melted hot running.

Not really since that is the intake side of the engine, but putting some heat shrink or thermal heat sleeve, if you have it lying around, won't hurt.

[Cubieman]

Just make sure you wrap up the wires well as noted.

Initially I didn't do such a great job with this and had water get into the harness, work it's way down, and an error for the EGT sensor occurred after washing the car.

Your loom will more or less be split directly under the driver's side drain for the cabin air filter so just do a good job sealing things up and you will be fine.

[Maxhouse97]

What did you use to seal it? Electrical tape or something else?

[Cubieman]

I used TESA (fabric tape) and corrugated wiring loom with zip ties for good measure.

Some have used these clamp on style T shaped pieces to better protect the area where the wiring splits and goes down the driver's side of the engine.

Something like these, you would want to get the correct size if using the plastic "T's".

[D-O]

Self vulcanizing tape to wrap and seal.

BMW runs the harness down the driver side on the euro spec cars. There are plenty of spots to secure it.

[Cronenberged]

I used a roll of wiring loom from O’reilly’s and used some scissors to split the loom all the way to were the wires come out the drug bin. Then routed them down the driver side like OE, Resealed, and sealed the new loom with zip ties. In the future I plan to refresh the engine and parts under the hood so when it’s out I’ll do a cleaner fancier set up, but for now everything is protected and clean no issues.