Hi All,
Re. O2 sensors for 1997 Discovery, AEL:
Can anyone say if extending the O2 sensor harness length 30" would have a negative affect on the accuracy and effectiveness of the sensor? There is an obvious reason why it would be a benefit on the LH upstream harness, but in my case, it's a problem with the RH upstream harness that makes this a near necessity. A previous owner cut that harness and spliced and taped it back together. By the way, it was a writer in this forum in 2012, https://landroverforums.com/forum/me...daedrix-45750/ who found this harness extension, making this fix possible for me.

 

So long as the wiring connections are sound, there is no problem. If the connections are weak/loose, of course then there is a problem.

One pair feeds power to the heater when engine is cold, so more wire mean it might take a fraction longer to heat up. Second pair of wires is the signal, very low amps; so no problem there. Monitor the O2 trends on your OBD scanner after you make the mod, just to be sure all is still good.

 

Just do not solder the wires. Odd, I know. But O2 sensors get there reference O2 reading via the wires. Apparently soldering will seal up the air gaps and you can end up with issues. I am pretty sure this was the issue I had with my V12 BMW O2 sensor codes, I soldered the extension and never knew this and I never, ever solved the issue (sold the car)

Solder and solder flux will close the air-gaps between the strands of wire and the O2 sensor may malfunction. So there you have it, soldering stops the sensor from 'breathing' through the wire properly....

 

Thanks, Dakota. In my case, the existing RH harness has been snipped off by the previous owner. There is no longer a plug on that line. I was expecting to cut off the corresponding plug on the new extension harness, and mate it with a nice solder joint. I'm not sure how else to make that connection? What would be an alternative method?

 

Thanks, John. The interconnect plugs on the extension harness seem to be perfect. It is 30" long and has plugs at both ends that seem to mate with the plugs on the Discovery perfectly. I've tested and the new Sensors I have click right on.

There are some photos of it in daedrix's 2012 post, here: https://landroverforums.com/forum/di...-repair-82684/

 

I would use simple crimp style butt connectors. They will allow enough air to pass. Even could be covered with waterproof heat-shrink.

I bought generic O2s from Bosch years ago that did not have vehicle specific plugs. Came with a kit (3M I think) that you spliced on to the old plug end. Cost less than with an OEM plug, which was important to me back then. Now my time is more important than cost.

 

Yeah, crimp and cover is best.