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Discussion Starter #1
I have a 2002 E39 that I am trying to put cut outs on. In order to do this precat the muffler shop said that I would need to relocate the O2 sensor ahead of the cutout. I was under the beast today and it looks like there is space right after the union of the 2 cylinder pipes on each side. This would be about 8 inches north of the cut out, but the existing O2 sensor would be about 12 inches short...depending on routing.

The alternative would be to splice in a 12" section with some heat shrink tubing....but I do not know if the additional wire would cause a difference in the resistance of the O2 sensor or if the wire only transmits data...?

Any thoughts would be appreciated.
 

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I doubt that 12" of good wire would cause enough resistance or voltage drop to cause any problems. I would be more concerned about the temp of the exhaust gases 12" closer to the headers.

I have an OEM exhaust, but I'm wondering what other people with full custom exhausts have done with their 02 sensors...
 

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maybe see if you can buy that connector from the dealer.

If not, maybe you can get a connector from another auto manufacturer (Audi, Ford, etc) Then buy an 02 sensor for that car, and use your old O2 sensor connector to make an adapter.

And you have to be sure to weatherproof any connections in the system. I tried soldering O2 wires, but it wouldn't stick, probably because it's stainless. Which means butt connectors, so you would need to get the kind that have the glue in them and shrink with heat.
 

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Discussion Starter #4
well Are the after cat sensors usable ahead of cat or do they operate in a different temp range? they have longer cords, but probably not enough to reach the whole way??? I will have jack the car up again and look.
 

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the after cat sensors are the exact same as the pre-cat sensors, pretty much any 4-wire O2 sensor will work. They might have different connectors though.
 
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