Extending O2 sensor harness/pigtail?

I'm doing a pretty substantial exhaust overhaul and as part of that, my O2 sensors will be moving and I'll need to extend the upstream harness ~1', and the downstream harness ~3'.

I figured it'd be just a simple solder/splice job but the more I read, the more it seems as though the sensor pigtail wires aren't typically copper... And it's even rumored that the wires serve as a fresh air supply to the sensor (which soldering would restrict and cause problems)?

The last part seems like a crock of s*** but I've seen it come up enough times to worry.

The sensors in question are NTK/NGK 23099 and 23506. I'd much rather butcher the sensor pigtails than the vehicle harness.

I've considered extensions but can't find anything Jeep-specific... Looks like Fords use the same connectors so I might pursue that route if soldering is out of the question.

Thanks in advance, dudes.

https://www.youtube.com/watch?v=ex1Hki6-NHw

Looks like Bosch comes out and states it pretty directly in their universal sensor install instructions above. Time to find some bare crimp connectors.

You can cut/splice the vehicle harness side, not the O2 sensor side.

Talyn said:

You can cut/splice the vehicle harness side, not the O2 sensor side.

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Why do you believe this is true?

The universal ones come with a harness you must piece together.

If the extension is done right, with the right wire it will be fine.

Because that is the way its done? The vehicle harness is just regular wire, not the O2 sensor wire. And the universal ones are crap.

It seems as though all available info points toward modifying the vehicle harness as the ideal solution (due to the oxygen reference theory, as well as the consistent theory that the pigtail wires are stainless or something other than copper). I'm reluctant to make permanent modifications to the vehicle harness in case these modifications ever need to be reversed (which is the preferred way to do it).

Fortunately, I spoke to a super-friendly tech at Casper's Electronics this morning, and they will make me a custom ~60" Dodge O2 sensor extension harness for $30 or so (with next-day shipping if I get the order in on time).

Time to hang the exhaust and take some final measurements.

Since our heeps use the Gm weatherpack style of connector, Why not make plug n pray extensions, using the same style of connector?
Is that harness they are custom making for both O2 sensor, or just one?

I could go that route, but at only $30/pop, I'd rather not spend the day in the junkyard and soldering.

The harnesses will be separate - basically I need to route the bank 1 upstream/downstream sensors to the factory locations of federal-emissions XJs. The upstream bank 1 sensor connector is right by injector #1, and the downstream bank 1 sensor connector is down where the federal upstream sensor is (with the connector bracket coming off the driver side of the oil pan).

From there, I'll be running APN headers, and a '97 XJ exhaust from there on back. If anyone wants specific part numbers and schematics (the required ECU, etc), PM me, as this technically renders my vehicle to be an "off-highway vehicle" and could be questionable to post in this forum. This just allows me to retain the 50-state emissions harness I have, unmodified, and not get a CEL due to the absence of bank 2 sensors (without the use of simulators).

Not really sure where going to the JY comes into play. But the Weatherpac connectors and components can be purchased at any local auto parts stores and online. But that is a reasonable price to not have to do the work.

anthrax323 said:

I could go that route, but at only $30/pop, I'd rather not spend the day in the junkyard and soldering.

The harnesses will be separate - basically I need to route the bank 1 upstream/downstream sensors to the factory locations of federal-emissions XJs. The upstream bank 1 sensor connector is right by injector #1, and the downstream bank 1 sensor connector is down where the federal upstream sensor is (with the connector bracket coming off the driver side of the oil pan).

From there, I'll be running APN headers, and a '97 XJ exhaust from there on back. If anyone wants specific part numbers and schematics (the required ECU, etc), PM me, as this technically renders my vehicle to be an "off-highway vehicle" and could be questionable to post in this forum. This just allows me to retain the 50-state emissions harness I have, unmodified, and not get a CEL due to the absence of bank 2 sensors (without the use of simulators).

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Johnnie Walker said:

Not really sure where going to the JY comes into play. But the Weatherpac connectors and components can be purchased at any local auto parts stores and online. But that is a reasonable price to not have to do the work.

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Touché. Didn't think about that. I'll see if I can snag both males and females locally since I've already got the wire from an unrelated project.

Do you know of any retailers who sell the woven mesh heat-shield sleeves that are on most O2 sensor harnesses and pigtails? Haven't seen them at local shops, but will keep an eye out.

Not sure on the mesh, but you could wrap them with the metallic type heat shield stuff people use under hood for injector and manifolds

Talyn said:

Because that is the way its done? The vehicle harness is just regular wire, not the O2 sensor wire. And the universal ones are crap.

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:dunno: That's odd. I have used universal fit one in the past with absolutely no trouble. Lasted until I got rid of said vehicle *years*. :dunno:

OP, the price of o2's is so cheap why don't you just find the correct type that already has a longer harness and use that?

Or you could just cut and splice the o2 side and if for some reason that does fail then replace it with the type mentioned above.

anthrax323 said:

https://www.youtube.com/watch?v=ex1Hki6-NHw

Looks like Bosch comes out and states it pretty directly in their universal sensor install instructions above. Time to find some bare crimp connectors.

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Interesting video.

The one you linked makes it sound like air is drawn in THROUGH the wire yet this video shows the air being drawn in BETWEEN the wires, which makes way more sense.

https://www.youtube.com/watch?v=Fl3aD1qJrEg

firehawk618 said:

:dunno: That's odd. I have used universal fit one in the past with absolutely no trouble. Lasted until I got rid of said vehicle *years*. :dunno:

OP, the price of o2's is so cheap why don't you just find the correct type that already has a longer harness and use that?

Or you could just cut and splice the o2 side and if for some reason that does fail then replace it with the type mentioned above.

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That's where my limited O2 sensor knowledge definitely shines. How many different styles/types of O2 sensors were used in various vehicles in 2001? I know the part numbers are for extremely similar sensors, but with different connectors and pigtail lengths. Ultimately I didn't really pursue this due to the fact that I assume (perhaps incorrectly) that no sensible manufacturer would require an O2 sensor with a 60"+ long lead... Seems like they'd try to get the engine harness to within 24" or less of the sensor location.

I now have a few used, functional NTK spares from a couple 97+ XJ donors, so I'll be chopping into the wiring to see what's true and what's lore.

firehawk618 said:

Interesting video.

The one you linked makes it sound like air is drawn in THROUGH the wire yet this video shows the air being drawn in BETWEEN the wires, which makes way more sense.

https://www.youtube.com/watch?v=Fl3aD1qJrEg

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Hmmmm... The video you linked seems to uphold a sub-variant of the "don't solder" opinions, which is "don't solder too close to the sensor itself".

Either way, I've been sidetracked with other crap and am only 50% torn down to pull the intake manifold at this point. In this process, I also found that a few injectors rotated damn near *freely* within the intake manifold and fuel rail using just my fingers, so old/worn injector O-rings might have been a contributing factor to my heat soak/vapor lock issues.

Do as you wish in cannibalizing used senors for science. I think that since you already have wire, and buying connectors/components is minimal in price also, that you should make your own. Would make for a clean install, not ruining perfectly functioning sensors, and cheaper than buying universal/other sensors.
Any of your local parts stores should have a set of replacement o-rings for your injectors. Only a few dollars at most, but if they are not leaking then they are most likely not the cause.

FYI, the downstream sensors for a plymouth breeze have a long (42" i think) pigtail with the correct plug.

Is that just a tidbit that you have personal experience with, or do you have a resource that details things like that? I'd love to be able to look through an application chart and find an ideal match.

I had a similar issue as you seem to be running into. I went to several of the local auto parts stores looking for a catalog. Oreily's had the Bosch book handy and let me page through it looking at different specs. Its a pretty good book, has pictures, plug styles and harnes lengths all listed.

The Breeze sensors listed as what I needed, and were the same price as the stock Jeep standard item. I ordered them and they worked fine.