PeachParts Mercedes-Benz Forum - View Single Post - How can I check the O2 sensor for correct operation?

yambrovich · #1 03-09-2001, 07:20 PM

My wife just called me from the side of the road using her cell phone (don't get me started on WHY that's now a requirement!!). The car = 1992 w201 190E 2.3
The red O2 sensor warning light just came on in the dash. Car has almost 180,000 miles on it (3X 60,000 miles) so I thought that it's just the speedometer tripping it for a checkup.
Just to make sure I'd like to check it out. On a former vehicle my mechanic disconnected the wire leading from the sensor and connected a digital multi-meter to it and read the output value. If I remember correctly he had is set on the DC scale with a small value and it showed .7 volts(?) which he said was "right in there" - no need to replace it.
Can someone (MB Doc, Steve, Aaron) tell me how to go about this on this car, what setting to use on my digital multi-meter and what the value should be if it's working correctly?

As always, the help I've received over time on this board is nothing short of AMAZING! I so appreciate the people who take the time to give us the feedback we desperately seek. Thanks again. I look forward to the feedback.