Oxygen sensor substitutes - Revisited

Went to Oreilly Autoparts tonight and picked up the Bosch 13942 Oxygen Sensor (for a 1990 Ford Taurus, 5.0 liter Mustang, etc). Here is my question:

-From past posts everyone says you can use this sensor. But it is only a 3-wire sensor. The 1991 535i has a 4 wire. The 4th wire on the BMW sensor is Grey -- I am assuming that is ground? So will this 3-wire Ford sensor work? Do you just not use the gray wire on the original BMW Oxygen Sensor harness?

Thanks
Jeff
1991 535i

You need to get the one with 4 wires... any 4 wires O2 sensor wil work.

Well, all the e34 535's have a 4 wire sensor. And from the posts I have read by those who have gotten the Ford 13942, they have not had any problem making it work. So I just need to know how they have gotten it to work when it is only a 3 wire sensor.

Thanks!

Quote:

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Originally Posted by Tiger

You need to get the one with 4 wires... any 4 wires O2 sensor wil work.

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Can anyone who had posted that they used the Ford sensor answer the question about the 3 vs. 4 wire issue?

Here's a wiring diagram for the different O2 sensors from NTK:

4 Wire has a sensor ground while a 3 wire does not. If you were to adapt a 3 wire to a 4 wire, you would have to make sure you had the sensor ground wire coming from the computer properly grounded.