S40 V40 Parts: S40 P1 Oxygen sensor PO141/Lambda sensor

[canis]

Originally Posted by oliverpervasive

many tell me it will not work as 1) air is taken in through the wires? 2) changing wire length could effect the resistance

Poppycock! Air in the wires? Who told you that?And, alright, yes all wire must have some resistance, but it's too little to measure. Put an ohmeter on it and try, I bet it reads zero. The extra resistance brought by an extra inch or so will be unfathomably small.

I think whoever told you that is confusing it with coaxial, where resistance is mildly important, in that several yards of the stuff can mean improper signal carriage.

Anyway, soldering the wires worked on my car. Now, this is important - solder does affect resistance, so join the wires physically (i.e. twist together) then solder them afterwards. That way the current never leaves the copper. For that matter, glue would work just as well.

[bobthecabbage]

Most O2 sensors do get their reference o2 signal via the wires. I'm not sure whether it permeates through the insulation or what but that is apparently how it is done.

That is presumably why an exhaust leak anywhere near the sensor causes false readings/poor running.

I'm sure that however you join the wires, as long as you seal it against water ingress by using some heatshrink over the join, then you will be fine.

[druid]

Nice to see where it is IN the car as i have only ever done this from under the car.

[oliverpervasive]

Hah - Although I think it is handy for people to see where the connector is under the front passenger seat- I suspect life would have been easier if I had wiggled it out from underneath as suggested by ww1dm1. It was only held in place by a piece of tape just beyond the grommet.

https://www.youtube.com/watch?v=ex1Hki6-NHw - here is a Bosch vid which refers to the air taken through the wires.....

I will try to rewire the old part but may not use solder - think crimp and heat seal is the way - just waiting for my sensor socket to crack on.

[ww1dm1]

Originally Posted by canis

Poppycock! Air in the wires? Who told you that?And, alright, yes all wire must have some resistance, but it's too little to measure. Put an ohmeter on it and try, I bet it reads zero. The extra resistance brought by an extra inch or so will be unfathomably small.

I think whoever told you that is confusing it with coaxial, where resistance is mildly important, in that several yards of the stuff can mean improper signal carriage.

Anyway, soldering the wires worked on my car. Now, this is important - solder does affect resistance, so join the wires physically (i.e. twist together) then solder them afterwards. That way the current never leaves the copper. For that matter, glue would work just as well.

No, modern zirconia type O2 sensors do take their air reference through the wiring. I believe it's done through the connector, not that much air is needed. Fixing is probably possible, it's just easier to mess up. And the worst part is that you may not find out that you messed up, as it may work anyways, but not exactly as intended.

Resistance will probably change from soldering, but I wouldn't believe the change would be significant enough to matter, extra 0.1ohm won't drop a 1V signal that much. Glue is not necessarily a good idea. Random liquid type super glue will just wick into the wire strands. Hot glue could work, but I don't find it very reliable in general.

[oliverpervasive]

I may try one of these to make the bridge on the old sensor
http://www.ebay.co.uk/itm/1224372405...%3AMEBIDX%3AIT

As you say the other issue is that both the replacement and the (to be) repaired item may work but not to the originals spec. I guess the only way I could know that is to do a before and after live readings using VOL-FCR which I cannot as its after the event.

[oliverpervasive]

Using a multimeter - set to 200omh - I got a reading of 06.3 from the red and yellow wires connected to the sensor end - which gives me hope this may still be a functional

[bobthecabbage]

Originally Posted by oliverpervasive

I may try one of these to make the bridge on the old sensor
http://www.ebay.co.uk/itm/1224372405...%3AMEBIDX%3AIT

As you say the other issue is that both the replacement and the (to be) repaired item may work but not to the originals spec. I guess the only way I could know that is to do a before and after live readings using VOL-FCR which I cannot as its after the event.

I wouldn't bother with the waterproof connector as you will never get the four wires sealed.

Your best bet would be to use crimp terminals and then some glue lined heatshrink over the top. Or even better use the ready made ones such as these.

https://primetools.co.uk/product/red...FdMW0wodHlwEkA

However the only caveat I would mention is that they need to have the glue lining to make them waterproof. These might have it and probably do but it doesn't state that. Wouldn't make sense not to have it though?

Other than that you could find the right four way econoseal male/female connector and do a professional job!

http://www.polevolt.co.uk/acatalog/E...onnectors.html

Not too expensive really.

[canis]

Originally Posted by ww1dm1

No, modern zirconia type O2 sensors do take their air reference through the wiring. I believe it's done through the connector, not that much air is needed. Fixing is probably possible, it's just easier to mess up. And the worst part is that you may not find out that you messed up, as it may work anyways, but not exactly as intended.

You could very well be right, as last year mine only just scraped the emissions test. I'd put it down to engine wear. I'm confused by the physics though. Does this mean the outer sheath is a tube and the reference air is drawn from under the carpet?

I'm intrigued now.

[bobthecabbage]

Originally Posted by canis

You could very well be right, as last year mine only just scraped the emissions test. I'd put it down to engine wear. I'm confused by the physics though. Does this mean the outer sheath is a tube and the reference air is drawn from under the carpet?

I'm intrigued now.

The air travels in between the copper strands of the wires. Where it actually gets in I'm not sure. Sounds like maybe it gets in via the connector.
I don't think you need much as its just the reference. It doesn't need to be rapidly replenished. It's just diffusing like a fart in a crowded room.