Originally Posted by clempot911
Itís just a way to bench test them Ė you can do the same on the car, forcing it rich/lean, but this is good if you have one on a salvage engine or a used one you saved and want to know if itís good or not. If the heater element is bad it doesnít matter anyway, he needs a replacement.
These guys did a video on how it works.
If the fuel system is working right and the O2 sensor reads 0.1v or less you have a dead sensor. It should be swinging above and below 0.5v if everything is working. The switching is fast, some cheap meters can't show it.
Yes, and the best way to test the Oxygen Sensor (not heater element) is with an Oscilloscope. You're able to view the switching rates (cross counts) of the sensor. The sensor is also checked for its rich-lean and lean-rich switch times.
There was a guy who wrote an article recently in 'MOTOR' magazine about it. He said to make sure you heat up the engine properly, then do a test at 2000 RPM. ...here's a little bit from the article.. He was testing a Civic:
"I described one type of oxygen sensor check
in the August column; Iíll suggest another one
momentarily. To recap that first test, hold the
throttle at a steady 2000 rpm and scope the O2
sensor. Usually, a good sensor shows three traits
during this test: First, the signal repeatedly and
consistently cycles rich/lean. Second, it makes at
least seven or eight rich/lean cycles within 5 seconds.
Third, the signal ranges from about .10
volt up to .90 volt. The scope pattern on page 12
of the August issue shows a prime example of a
good oxygen sensor signal."
Some tech's will not let the sensor heat up to the proper temp and they will not make the best diagnosis or be able to see a lazy, or bad Oxygen sensor.
You can also do a snap-throttle test to check for a "lazy" O2 sensor.