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How to test O2 sensor?


NAXJA Forum User
Grand Rapids, MI
I've done a search and have had difficulty finding a thread that lays out how to test the O2 sensor on a 96xj. What are the mesaurements for the fore and aft O2 sensors, in relation to the catalytica convereter. I replaced my fore O2 sensor quite some time ago when I did my header...probably 30,000 miles ago, and have yet to replace the the aft O2 sensor...it's original with 136,000 miles. I read that the aft O2 sensor just monitors the cat. and doesn't aid with the performance of the engine. When my old cat went bad, sounding like a can of marbles, it never threw a check engine light. I want to test both of them to ensure that they are operating properly, especially since my daily commute has increased by 60 + miles.
The signal is an alternating voltage which you need a high impedance meter to look at (and you can do damage with a cheap meter..)

However, there really is no point to testing it if your computer hasn't thrown a code..

It is possable for these things to be out of calibration (contaminated) and still producing a normal signal. The only way to see that is with an emissions test.