O2 sensor question

[slo325i]

Hey guys,

I'm trying to replace my O2 sensor on my '87 325i. I've called my local autozone and they told me that their O2 sensor has 4 wires attached to them. But here's my question.

I only see two wires attached to the O2 sensor itself. Then when I trace the wires from the O2 sensor back towards the firewall, it seems to join other sets of wires. Where do I start with this? Why is there only two wires on the sensor? Please help...

Justin

[netcsk]

Does the connector for your O2 sensor (the connector closest to the sensor) have four wires? Your sensor should have 4 wires. Two wires are for the reading (voltage output and ground) and two wires are for the heater (Voltage in and ground). If you are missing any of these, the sensor will not operate correctly. Missing heater means that the sensor will not operate when cold. Missing the reading wires means that your computer is running off the internal fuel map with no fine-tune adjusting.

Follow these other set of wires to see what is going on.

[slo325i]

i think the previous owner hacked with the O2 sensor as well. Explains the bad mpg... thanks for the quick reply!!!

justin

[///M42 sport]

http://www.boschautoparts.com/NR/rdonlyres/3BB8A8FA-C707-4333-9098-727C01AF4B7D/0/OxygenSensorInstall.pdf

CHeck this out. Bosch writeup on how to splice their sensors haha.

[slo325i]

Ok, i found the problem. It's supposed to be a four wire unit and the two wires were disconnected from the O2 sensor. Anyone have a used O2 sensor for me?? I heard that there was a mustang one that I could use. I'll search.

[netcsk]

That's one item you shouldn't buy used. They have a life to them, so you won't get a good return out of a used one.
You can buy a universal sensor from bosch and wire it up like the PDF above states if you're looking to save some money.
I do believe there is a mustang one as well, but you will still need to change connectors.

[Adrian_Visser]

Well if that isn't proof that universal O2 sensors work the same as the OE ones that cost twice as much I don't know what is. There is so much conjecture around that the universal O2 sensors don't work the same, that is a good debunk I mean straight from the manufacturer.