swapping genuine o2 sensor for universal

[Leo]

hi, i just bought a universal 3 wire oxygen sensor for my wrx and swapping them over is just a cut and crimp job but the original has a red, a white and a black wire and the one i'm putting in just has a black and 2 whites...? can anyone help?

cheers

[buddah]

I just did the same thing in my RB25DET (obviously not a wrx but same principal).

This is a fairly simple way of doing it but it worked;

So the black wires go together, then I just lined up the position of the other two wires in relation to the black one.
So if you are looking at the top of both the O2 sensors beside each other, and the black wire is at the top. Then the wire that is on the right (say red on the original sensor) connects the the right side white wire on the universal sensor. And the wire on the left connects to the white wire on the left of the universal sensor.

Make sense?

It worked fine for me, however;

The genuine sensors are programmed to operate within a certain range which is specified for that engine, where the universal ones are obviously universal.
I found mine worked fine for around 5000km's and then started to play up, and so now I'm going to have to go and get a genuine one.

Might be different with wrx??

[Gannon]

Buddah,... im a little sceptical of your methods.

On the universal sensor, the two same coloured wires are the heater wires. The other one is the signal wire.

What you have to do is find out what wires are the 12v heater supply wires and the wire to the ecu in the car side wiring.

Grab a multimeter and put it on the 20v setting and put the negative probe to the body. Now take the other probe and test the 3 wires with the ignition on.

Car side wiring---------------------------------Oxygen sensor
The heater supply should have about 12v-----(this connects to a white wire)
The heater ground should have 0v------------(this connects to a white wire)
The signal wire should have 0.5v-------------(this connects to the black wire)

[buddah]

Buddah,... im a little sceptical of your methods.

Understandably so, it is a fairly rudimentary method.

Car side Grab a multimeter and put it on the 20v setting and put the negative probe to the body. Now take the other probe and test the 3 wires with the ignition on.

wiring---------------------------------Oxygen sensor
The heater supply should have about 12v-----(this connects to a white wire)
The heater ground should have 0v------------(this connects to a white wire)
The signal wire should have 0.5v-------------(this connects to the black wire)

And proper testing with a multimeter would be the way to go. However you're still in the same position when it comes to which white wire on the universal O2 sensor is heater supply and which is ground. As you're only able to test the wires from the plug.
With the genuine sensor it is obvious because one is red and one is white. But the universal sensor I got didn't tell me which white wire is supply and which is ground. So how do you get past that?

Is it possible to test the unit itself?

[Gannon]

However you're still in the same position when it comes to which white wire on the universal O2 sensor is heater supply and which is ground.

Its just a resistive heater, so polarity isnt important.

It is however important to make sure you get the signal output wire (black wire) right. Mixing it up with another wire could fry the ecu

[AlpineRaven]

Its just a resistive heater, so polarity isnt important.

It is however important to make sure you get the signal output wire (black wire) right. Mixing it up with another wire could fry the ecu

Thats correct.
White wires are heater
Black is signal.
Cheers
AP