O2 sensor question

nightheart · nightheart's Garage

My O2 sensor is missing completely (hasn't been there since I owned the car) and my options sticker is gone as well. My question is are these hookups for a 1 wire or 3 wire sensor? I know the earlies had one wire, but I have three connections and might have a cali car. If the wires aren't all for the O2 sensor, what is the other connector for?

HondaDustR · 11-17-2008, 07:31 PM

Quote:

Originally Posted by nightheart

My O2 sensor is missing completely (hasn't been there since I owned the car) and my options sticker is gone as well. My question is are these hookups for a 1 wire or 3 wire sensor? I know the earlies had one wire, but I have three connections and might have a cali car. If the wires aren't all for the O2 sensor, what is the other connector for?

That looks different from the late 3 wire sensor hookup, but it looks like it does use a 3 wire sensor. The connectors look like they match the picture here.
http://www.the944.com/oxygen.htm

krystar · 11-17-2008, 09:37 PM

i have same connectors on my cali '83.

now the question is...is the 2 pair with black connector the signal? or is it the one with the orange connector?

HondaDustR · 11-18-2008, 09:52 AM

On the O2 sensor, the single black wire is the signal and the two white wires are to power the heater inside the sensor. It gets its ground through the exhaust to the engine. The double connector should be for the heater and the single for the signal.

many944s · 11-18-2008, 10:00 AM

^Correct. The two pin connector is for the heater on the O2 sensor (white wires) the single orange/yellow connector is for the single signal wire (black).

krystar · 11-18-2008, 10:24 AM

great thanks..i hope OP's question got answered too heh

nightheart · nightheart's Garage

Yep, I got my answer, not really the one I was hoping for, since now I have to buy the expensive version. Kinda cool to know my 944 made it from cali all the way to PA, though.

Zero10 · 11-20-2008, 09:23 AM

WTF? I have never seen the 2-pin connector beside the 1-pin before. I thought all early's had 1-wire O2 sensors! Learn something new every day.

The ECU won't know if you replace it with a 1-wire, and the only difference is that it takes a few minutes longer to warm up, so you will probably get slightly worse mileage using a 1-wire sensor over a 3-wire, but once the engine is up to temp it will be no different. If cost is that big of an issue I don't see why you couldn't go this way. A good secondary plan would be to buy a dead one off somebody (or pull it at a wrecker's), cut the connectors off it then splice in a universal 3-wire sensor. That should set the total price tag at around $50.

I just looked through the pelican catalog and I do not see the correct O2 sensor for your car listed there, all the ones listed have the 3-pin connector for the late cars, except maybe the first one (but it says it fits 83-88, and the connector changed in 85.5)

HondaDustR · 02:21 PM

The other difference is the non heated ones are only good for about 30,000 miles, whereas the heated ones have a life expectancy of 60,000 miles. I guess the heater, which is there to keep it at operating temp (600 deg F) also keeps it cleaner.

nightheart · nightheart's Garage

Quote:

Originally Posted by Zero10

WTF? I have never seen the 2-pin connector beside the 1-pin before. I thought all early's had 1-wire O2 sensors! Learn something new every day.

The ECU won't know if you replace it with a 1-wire, and the only difference is that it takes a few minutes longer to warm up, so you will probably get slightly worse mileage using a 1-wire sensor over a 3-wire, but once the engine is up to temp it will be no different. If cost is that big of an issue I don't see why you couldn't go this way. A good secondary plan would be to buy a dead one off somebody (or pull it at a wrecker's), cut the connectors off it then splice in a universal 3-wire sensor. That should set the total price tag at around $50.

I just looked through the pelican catalog and I do not see the correct O2 sensor for your car listed there, all the ones listed have the 3-pin connector for the late cars, except maybe the first one (but it says it fits 83-88, and the connector changed in 85.5)

I thought about that, but there is enough rigged on this car, that I'm trying to everything right. Local napa store has them for 145.....too. I think all cali-cars from 83-88 had the same sensor, except the 951. I'll probably order one locally, easier to return if I'm worng. I'll hook that up along with the MIA cat sometime this winter.

cauzomb · 08:46 PM

Sorry to dig up an old thread, my early 83 has the same sensor connectors, except missing the orange/single pin connector, the previous owner had spliced in a 1 wire o2 sensor and left the heater wire connector dangling, and completely cut off the orange conector where they spliced in the single wire o2 sensor.. What I have left at the wiring harness is a fat green wire, with two connductors, looks like a coaxial wire.

When I was removing the old 1 wire sensor, to replace it with a new 3 wire heated sensor, I lifted up on the crimped on one wire connector at the main harness, for the signal wire of the o2 sensor, and the crimp on connector just slipped right off that green wire with no effort at all.. This probly why my car ran so funky..

The green wire is dirty and oily looking.. after reading a few different posts and info pages about the 944 o2 sensor/replacement sensors.. I found info about how the sensor draws reference air from the wireharness.. I'm thinking since the factory harness is contaminated with oil it will no longer provide the "clean air" that the o2 sensor needs through the wire harness.. however, that orange one pin connector looks to be hermetically sealed to the single pin connector, and the single pin connector looks like there is no "air hole".. I'm not going to attempt to replace the orange connector, but It looks like I might have to dig into the harness a bit to find clean wire, then pig-tail a new section of wire to feed to the o2 sensor, Is that sensor plug completely air tight?

Also, the green wire has two condutors, "coaxial" I'm wondering what this coaxial wire needs in regards to a connector/sheilding and all... What wire is used for the signal? center conductor?

Thinking if it's a shielded wire, the coaxial connector needs to have the shield "outer conductor" to ground, and the center conductor is for the signal of the o2 sensor.. is that right?

Does anyone know how the old connector works? is the body of the orange plug connected with the outer coax conductor as a shield to ground at the engine bay?

338WIN · 12-03-2009, 09:18 PM

Didn't catch what year your car was, but I just did this with my 83. I know it was a single wire even though it has the three wire hookup as illustrated. My orange plug was broken and I used a connector for the fat green wire you are talking about and another to connect to the one wire Bosch sensor. Used shrink wrap around all the connections and it works great.
It was an easy $20 solution to a loping idle.
My understanding is that all the two wires do is heat the sensor so it operates sooner. I'm willing to be corrected if wrong.
I know it is the fat green wire because my single pin connector was in place but broken.

krystar · 12-03-2009, 10:25 PM

338win's correct. the 2 wire connector is for heater. and the orange plug's center wire is the signal. outer is just shielding.

cauzomb · 12-03-2009, 11:53 PM

Thanks for the quick reply, and for the info about the green wire.. I appreciate it..

Had to stop when I wasn't certain which green conductor was what..

I'm exchanging my 13953 for the 15725 part as soon as I can get one..

Couple more quesitons.

Does the body of the factory connector tie in with the green wire's shielding, where the connector bolts/clamps to the firewall, as like a shield to ground connection, or is the shield just stop/open at this end/ no connection to the shield/plug/firewall..

Any idea if the factory orange/yellow o2 sensor signal wire connector is sealed, blocking the o2 sensors claimed required airpath?

This won't be a problem on my install, considering I don't have that plug anymore, but some other people might get a heads up, somehow by knowing if it's sealed or not..

Regarding the posi-locks that come with the new part number..

Seems to me that the posi-lock connectors are sealed from one end, to the other, via the cast in place center conductor.. After looking at the line drawings; they don't apear to have a path for airflow between the center/threaded body casting and pressure contact section, from one side to the other....

Is there a hole in the needle shaped center conductor of the posi-locks, from one side to the other? I may just ask posi-lock about those, but I have some carb jet drils that I could use to add a through hole in the center section/s cast body, right next to the center conductor

If it's just required that the o2 sensor has "clean air" rather than a constant consumable supply it wouldn't matter if it wasn't a through hole design, but if they do infact breath and need to pull air through the wire harness, all the way from the cabin/dme.. those connectors don't look like they provide it..