Is there a test for the O2 sensor?

[bower100]

Before replacing the catalytic converter I'd like to know the signal to the ECU is right from the 02 sensor. (I remember reading ,or testing, others with a dc volt meter).

Something about a 02 sensor has a 0-10 DCV range and a proper air/gas mixture should be around 5 volts? And what initial voltage should be expected when first "keying on"?

Is there a place under the hood ,mayby near the ECU where I can probe the wires from the sensor rather than doing it right at the bung-hole in the exhaust pipe?

Thanks guys, dave.

[ranger5.0]

I believe at a cold start the O2 sensor isn't activated cause of the enriched mixture to help it start. Most newer rigs have thermoacitve O2 sensors.( When I mean newer anything from the 80's and up) Though they were not used in all apps.

[bower100]

I guess that makes sense. Prolly the ecu just ignores the voltage feedback from the o2 sensor until it finishes it's start-up "sequence"... fast idle and all.

Another question..... I'll new post, so it's not lost here. dave.

[84_4x4]

a bad 02 should send a fault code to ecu and turn check engine light on

[bower100]

Yeah, I guess it should. Just looking for reasons for the BII's habits.
dave