O2 Sensor Testing

[Michael Eck <meck@ptd.net>]

I was going through books at the bookstore yesterday and came across a
book that gave a way to test oxygen sensors. Has anyone tried this
before? Is it accurate? Any corrections or additions?

1. Warm up the engine to normal operating temperature.
2. Disconnect the oxygen sensor wire. (what about the ones with more
than one lead? I suppose the heater element should be left alone?)
3. Connect a voltmeter to the sensor. The engine should be running in a
lean mode and the voltage should read near zero.
4. Put a 1.5v battery in place of the sensor. Minus to ground, positive
to the wire going to the computer.
5. The engine should switch to a rich mode and the sensor should read
near 1v.

If the voltage doesn't change coming from the oxygen sensor, the book
says it's bad and should be replaced. If the voltage swing occurs, the
sensor's OK.

So that's what the book says... What do you all think?

Michael Eck
86 5KCSTQ   184k
88 GTI 16V   40k and parked for the winter!