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Re: O2 Sensor Check... How? (archive)
[ Follow Ups ] [ E30 M3 Message Board ] [ Msg. Board FAQ ]
Posted by John Arnold on November 24, 2001 at 22:06:24:

In Reply to: O2 Sensor Check... How? posted by George on November 24, 2001 at 21:16:13:

To check the oxygen sensor:
1) Warm up the car to operating temperature.
2) Unplug the oxygen sensor.
3) Hook the positive lead of a digital voltmeter to the center wire coming from the sensor (other lead to ground). Set the meter range to read 0 to 2 volts.
4) Run the engine.
5) If the sensor is working, the meter should read between 0.1 and 1.0 volts...typically 0.6 volts.
6) To further check the oxygen sensor`s response to rich conditions, unplug the vacuum hose from the fuel pressure regulator where it plugs into the idle control valve hose (just above the "O" on the valve cover). Plug the hole with your finger. The voltage should rise to near 1 volt.

If the oxygen sensor reads no voltage, or if the voltage doesn`t change under rich conditions, it is faulty.
John
88 ///M3 Cinnabar

Is there a way to check to see if an O2 sensor is working properly? I'm running quite rich and wondering if replacing the sensor will help.

I asked my someone at a local dealer a while back and got: the check engine light will come on.

me: Um, e30 m3's don't have check engine lights.
them: Yes, they do.
me:riiiiiiight.

-g




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