I agree, Chuck. If this is anything but a quest for curiosity, get a new sensor in there so there's a baseline of expected performance.

However, if this is for "educational purposes," then look up the propane torch test for an oxygen sensor. Must be done removed from the car, of course, but it works. You can use the torch to clean the soot.

I also have connected one to a Simpson 260 series 6 - 20,000 ohms per volt, finding the load of the meter reduces what you read in voltage produced by the sensor, compared with a 10M input meter.

Analog or digital makes no never mind; the analog is easier to follow than bouncing numbers, but who (besides old hoarders like me) keeps a an old VTVM (vacuum tube volt meter) around these days. A scope is the best method, but for car folks likely to have a meter of any kind, it is their DMM (digital multimeter) that will have the 10-meg input spec.

The sensor has to be hot - something like 600F IIRC - to output a useful voltage.

Another thing that fools people a lot on these Bosch systems is the ECU maintains a weak (current limited) 0.5V voltage on the oxygen sensor input sometimes called the reference voltage. The sensor has to be hot to overcome this with its own output and then vary it lower for lean and higher for rich.

By the way, I killed another sensor with an oil leak. This harkens back to our discussion of where the reference air is drawn from. There's this nice picture in the LH2.4 green book... showing where the oil wound up. The Bosch universals come with a really sweet splice box these days.




--
Art Benstein near Baltimore

"He's the best mechanic in town." - 1992 Annemarie Powell said of General Colin L. Powell, a Volvodad