Section 1 cats - O2/EGT relocation harness

[Corradoloco]

I made this post cats O2/ EGT relocation harness for my M3 that is now fitted with a euro spec M3 header and section 1 (cats). ZERO modification necessary to the original harness on my M3. Cabling runs along the same route as the euro spec M3. Post any questions and I’ll do my best to answer them for you guys/gals.

cheers.

[LatinSkllz]

I’m confused, are you selling this?

How did you extend the wires?

What type of wire did you use for both 02 and EGT? I thought the EGT wire could not be extended?


Sent from my iPhone using Tapatalk

[Corradoloco]

Hi Latin Skllz,

I didn’t consider selling them but I would if the price is right. In parts, I spent $260 CAD and about 3 hours labour.

The wiring used came from a donor X5 harness, this gave me the exact same wiring and terminals down to the wire colour/gage and production year as my harness and the required length to bridge the gap with no need for splicing. No splicing is key if you don’t want codes. EGT wiring also came from the X5 donor harness. The key is every single part used to build the harness is genuine BMW parts, making it a genuine harness hehehe.

it’s now installed and I’ve driven over 250km with no codes, in all types of driving. Also no dme coding for euro spec cats. A true plug and play solution. Hope this helps.

[LatinSkllz]

You posted this in the for sale wanted section so was unclear. Good job.

I’m trying to figure out extending the egt sensor.


Sent from my iPhone using Tapatalk

[IamFODI]

Thread moved to the general section. Thanks!

[Corradoloco]

You posted this in the for sale wanted section so was unclear. Good job.

I’m trying to figure out extending the egt sensor.


Sent from my iPhone using Tapatalk

sorry about that, I didn’t realize.

All you need is a M3 brake wear sensor male/female and one terminal plug part# 61131393742, two cables off a donor harness of the same type and gage.

[Tbonem3]

The original postcat and egt wiring reaches the eurosect 1 though

[Corradoloco]

I believe it does, but not using the original euro spec route and cable guide holder.

[Corradoloco]

The original postcat and egt wiring reaches the eurosect 1 though

And you likely need to modify the EGT harness, I can’t see how the EGT would reach regardless of the route you take. My approach was in effort to preserve the original harness, replicate the euro spec setup and keep it completely reversible with minimal effort.

[Tbonem3]

Mine reached, but you're right about not using the euro harness.

Are you not worried about extra resistance in the wiring? Not sure if you tested

[Corradoloco]

I did worry about that, I gave it a 30% chance of working with no error before testing, I took OCD levels of detail in sourcing the exact same wiring down to the production year, terminal connectors, terminal plugs etc… So far over the last 300km zero issues. I’ll report back if I do see issues down the road.

[LatinSkllz]

sorry about that, I didn’t realize.

All you need is a M3 brake wear sensor male/female and one terminal plug part# 61131393742, two cables off a donor harness of the same type and gage.

No worries man. Good job. What donor x5 did you get this? May try to hunt one down. I do have a spare s54 harness with the plugs I may try to salvage.


Sent from my iPhone using Tapatalk

[Corradoloco]

E53. I would use the s54 harness if you have one, this way you don’t need to repin one side of “new” EGT harness, but you need to make sure the harness will reach, you need about 6’ of wire