When they had unheated oxygen sensors could you tell if its not heated up?

Question

When they had unheated oxygen sensors could you tell if its not heated up?

Answer 1

NO.

The computer gives the O2 sensor certain time for it to warm up. Afterward it the data (from O2) sensor does NOT LOOK good, the check engine light comes on.

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You can get O2 sensor voltage monitor and if the voltage doesn't change (or just dead), then you can assume it is "not warming up" or just bad.

Good Luck...