81c3

I will need to lengthen my O2 sensors wiring harness due to adding headers. I have some old O2 sensors. Can I just cut the wires from the old ones and solder them together to get the length I need. Obviously, the wire gauge is the same, so the voltage through them should be consistent. Is this ok to do?

jv9999

I've always been told that you have to crimp the connections on an O2 sensor because the sensor get's it's reference sample through the strands. I've also heard that solder won't stick to many as they are a special high temp wire, not just copper.

PatternDayTrader

I would cut and splice the car side of the harness.

MatthewMiller

Agreed. The sample jv9999 is talking about is actual air/oxygen, which travels through the wire insulation to the sensor. I don't think you can successfully splice into the sensor wires. Take patternDayTrader's advice. Although I'm not sure whether it's better to cut and splice the car side of the harness, or just buy both connectors and fashion a plug-in extension to go between the car side and sensor side.

cardo0

I looked for this before and can't find anything wrong with your cut and solder for extensions. Though at one time I had thought I had read the wire was sensor specific I could not verify that. I would use a solder connection any day as crimp connections can become a voltage drop.

The precaution is to not cover the entry point for the wire as this is something like a vent port for the sensor to get fresh air that it uses in it's process. Often that end gets covered with sealer and a brand new sensor will fail.

Ed Ramberger

I worked with Bosch on O2 projects when I was at Mercury Marine. The O2 sensor gets a reference through the wire. You can't solder the wires of the sensor for several reasons: 1) It blocks the O2 reference, 2) The wires aren't meant to be soldered - they are not copper, 3) Trying to solder the O2 wires to copper wires and there will be dissimilar metals with a current flowing through them - not good in a circuit that operates on millivolts. Plus they won't solder well.

aklim

I don't think the O2 sensor is going to be an issue. I would do the extension with the solder way on the sensor side. I don't want to have an issue with cutting on the engine side if I had a choice. In 5 years, I'd toss the O2 sensor anyways. Now I have a Heated O2 so I had no choice but if I retained the single wire, I'd do it on the sensor side and call it a day.

PatternDayTrader

Seriously bad advice.

81c3

I bought new sensors. Problem there is that the new ones seem to be the same length as the old ones.... about 13" of wire. I havent received them yet, but Ill send them back if they arent ant longer.

If I were going to lengthen the wires, I would use the wiring from the old sensors so it would all be O2 sensor specific wiring. ( I have 4 sensors already) There would be no copper. However, since there could be an issue with voltage, I will not do it.

So if the new ones I bought are still too short, then what are all the LT-5's with headers using to make up the distance needed?

WhiteC1

I have a set of two 24" long O2 sensor extension harnesses, brand new. If you're interested, PM me.

Regards,
John

C6_Racer_X

Why not buy a sensor for an alternate application with the same properties, but longer wires?

Although getting an AC-Delco PT2336 (car side wiring pigtail with connector) and splicing/crimping on the connector from an old sensor would make a handy "extension cable."

cardo0

81c3 you are doing the right thing. The reference in the sensor is from the air inlet at the wire entry point and not carried on the wire as a signal. The wires only carry the potential difference (voltage) created by the cell. An O2 sensor is a voltage generator! You can easily Google that to see for yourself.
Solder does not block any signal and is one of the best conductors we have as it's used on every electronic circuit board on this planet! I have never read of something so rediculous! You should be wary of anyone that would make a claim like that for solder. And even though you will be soldering similar metals, solder can easily weld dissimilar metals. For strength I use J hooks with a little flux - using enough heat is the trick to a good solder joint. And cover a heat shrink for insulation - strong as heck - but remember to slide on the heat shrink before soldering.

MatthewMiller

You're misconstruing what was stated and misunderstanding how the reference air works. The air is carried through the wire insulation into the sensor, not as an electrical signal but as actual air circulating between the conductor and insulation. Here's one of many references about that:

So considering the above facts, what do you think happens to the supply of outside air flowing between the conductor and insulation if we flow a bunch of solder into that same void?
It doesn't block electrical signals (obviously), but it can certainly block the flow of outside air through the wire insulation because it will flow into the space between the insulation and conductor - the same voids through which the reference is supposed to flow.

Also...
...soldering is not at all the same as welding, just in case anyone gets confused by your post.

ctmccloskey

I totally agree with cardoO,
Having extended one or two and swapped ends, I know it can be done. Usually I just buy a new one, you are theoretically supposed to replace the O2 Sensor every 50k miles.
I was surprised at all the people who said "you can't do that". But, alas you cardo0 are correct, you can make extensions since the wire carries less than 2 volts in it signal. Great advice concerning the heat shrink, I use the "marine" kind myself as I drive a C3 Convertible.

The insulation on a O2 sensor does not have any significance or in any way help transfer the ~.75-1.5 signal voltage signal. It is a low voltage signal that goes through the wires whether they are aluminum or copper. I just installed a AEM fuel/Air Ratio gauge which required me to install a harness into my car, the gave me a harness that plugs directly into the O2 sensor. They even told me that you can shorten the harness if you needed to as they give you like 8 feet. If I can shorten one side why not the other? Solder does not weld, it joins things together. The man gave you great advice, don't stick to the air travelling inside the insulation stuff....

It is an electrical Sensor, nothing more, nothing less

81c3

Wow... lots of info here. I appreciate it from everyone.

So over on ZR1Net, I had a great member (Jagdpanzer) pretty much give me a 20" extension. I should get it next week hopefully.

That brings up the question..... if an extension has electrical connectors on 2 sides, wouldnt that be a place where ther would be no airflow under the insulation?
Im in no way trying to be disrespectful to you Matthew.... as you have given me sound advice in the past on suspension questions... Just wondering how that would work...

Thanks!!

littlesk8cracker

cardo0

It's called imagination engineering. There are at least 2 on this forum that frequently use this claiming to help others. Your better off using the ignore function to save yourself from pointless arguments and personal attacks.

MatthewMiller

No worries about asking questions or thinking critically. We're all here to learn from each other. Connectors like that won't be soldered in all likelihood - they'll have some kind of crimp connection for the conductors. The air can pass through the opening in the insulation where it terminates at connector. So I don't think the extension will carry the air, but the air can still enter at the sensor's original connector even with the extension. It's just that if you solder onto the sensor's original plug, at that point you run the risk of blocking the air passage. Note that in my link from the previous post it says that you shouldn't even use grease on the connectors because that could prevent the air from entering the sheath.

I'm not saying it's guaranteed to block it, but rather that there's a big risk of that happening and ruining a perfectly good sensor. Also, not all sensors use the wire's insulator to get reference air. Apparently newer ones are different. But I've known several people who've soldered extensions on their O2 sensors and they stopped working. Here's another link that references this more directly:

MatthewMiller

The last time you tried to say it was all imagination, I brought one reference after another, whereas you brought nothing - not one single citation of any actual facts or authoritative sources. When you continued to act like an ***, an actual subject matter expert (what we would call a "primary source") came in and told you that you were flat wrong. I notice that since he explained who he is and his technical and experiential background, you haven't been brave/foolish enough to post again over there.

Now we're onto a new subject and you've decided to act like an *** yet again. This, despite the facts that:

• I'm again bringing actual technical citations whereas you've brought nothing but conjecture;
• Ed Ramberger actually worked in the field doing O2 sensor research, and he also posted (post #6) the same thing a couple of us are saying about not cutting and soldering extensions onto the sensor's pigtail (are you really saying he doesn't know what he's talking about, like you tried to do to the industry expert in that last thread?); and
• You don't even understand how an O2 sensor works (thinking that "reference air" means an electrical signal) or what soldering is.

Keep up the good work. You're my hero.

81c3

Again, all responses are appreciated... Seems that the opinion on this is about 50/50 I posted on ZR1 Net Registry and its about the same. I was a mechanic professionally many years ago... I remembered learning something about never soldering O2 sensor wiring, which is why I raised the question to begin with. I also think that the air entering the sensor has to be free flowing directly where the wires enter the top of the sensor.. I just purchased new NTK sensors and the directions do mention not to impede air flow at that place on the sensor with grease or sealant of any kind.

But alas... I have purchased the pre made jumper and feel more comfortable using a plug and play piece rather than cobbling something together where milivolts are involved.

Please, no arguing over something like this gents.... were all adults and sometimes we just have differing opinions and have learned a different way..... no use in getting all angry with each other..

Thanks Guys!.