I'm a little peeved at the moment. I realize our cars use 3-wire heated oxygen sensors, and that's what I ordered. What I was sent was a 4-wire, though. Basically what I want to know is, can I use the 4-wire with the 4th wire not hooked up, or will it not function the same as if it were simply a 3-wire to begin with? For the life of me I can't find the answer anywhere on the .org or on Google or anything.

 

As far as i know, the wiring harness from the old one, can be spliced to work with the 4-wire, the catch is, you gotta know which wire connects to what wire. The 3-wire one is a direct oem replacement where it's plug & play.

 

Where did your order from. I have to buy an o2 sensor soon too

 

I have a dead OEM 3-wire sensor sitting right next to the new one. I'm using to make a plug-and-play harness for when I go to install it. I'll simply cut one wire from the old sensor/wiring at a time and splice it into the corresponding new one. Simple enough, eh? Then I just ignore the gray-colored 4th wire, right?
eBay. I bought a universal one for like $22 shipped or something like that, GREAT deal.

 

 

Looks fine to me, dude. Just make sure that you tape that thing up real good, so that you won't have any broken connections.

 

Soldered and wrapped up tight

 

cross your fingers & give it a try

 

My experience with universal O2 sensors on imports is that it is a wast of time and money. Didn't a piece of paper come with the sensor to tell what each of the 4 wires are? Usually 2 wires that are the same color are the ground wires. You can connect both of them up to the one ground wire from your harness or you may be lucky enough to chose the correct one. My experience as an Automotive Technician is they don't last long so don't be surprised to see your light come back on in the future for an 02 code. I would suggest an OEM spec replacement and not a universal.

 

^^^ Oxygensensors.com $75. for me.

 

This is almost entirely for the sake of passing inspection (since I can't have the code and pass). I only paid like $20, too, so big deal. Also, I've looked at diagrams of how oxygen sensors work, and with 3-wire heated oxygen sensors the two white wires are the heating elements and the black is the "signal." The gray wire on the 4-wire is apparently a ground, and I think that is simply a choice made by the car manufacturer (which to use...3-wire vs. 4-wire). I think the addition of a 4th wire for a ground is just a different "type" of circuit setup for the signal.
You can get OEM for cheaper than that.

 

Quoted from a Miata header install web page:

 

4 wire = A32b

3 wire = A32a


IIRC.. But I don't see how the 4 wire would affect the early A32 guys, now try using a 3 wire on a later A32 and then you have a problem lol.

--------------------------------------------------------------------


EDIT: Nvm, good luck and thanks I learned something.

 

Ignore the Grey ground, the heated element doesnt matter, it only completes a circuit so the only wire you have to worry about is the signal wire. Hope it works for you.

 

Yeah, but the heated element, if not working properly, would set off the CEL and throw a code, wouldn't it? I need to get rid of the code/CEL to pass inspection, so that would defeat the point of me getting it. I could really care less about functionality, I've had this sensor dead for about 6 months now.