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Old 11-07-2012, 07:19 PM   #2
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It might be more likely that your cat is just no longer doing it's job. You saw from that site you listed that the front sensor should fluctuate fairly quickly between 0-1V (actually more like .2ish-.8ish) DC and the rear should have a pretty steady and consistent reading of .5V DC. This can be pretty easily checked with a voltmeter/multimeter, but you'd need a wiring diagram to tell which wires to backprobe at the o2 sensor connectors. Two will have to do with the heater circuit and the other 2 will have to do with the signal the PCM is looking at.

I think this would be best way for the average guy to look at what the o2 sensors are doing. There're probably youtube videos that'd show you how to do this.
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