What does the post, or downstream, oxygen sensor (HO2S) measure?

[PhilipSeeMore]

Question 1

The voltage output of a zirconia oxygen sensor when the exhaust stream is lean (excess oxygen) is ________.
◦ relatively high (close to 1 volt)
◦ about in the middle of the voltage range
◦ relatively low (close to 0 volt)
◦ Either A or B, depending on atmospheric pressure

Question 2

What does the post, or downstream, oxygen sensor (HO2S) measure?
◦ Amount of H2O behind the catalytic converter
◦ Amount of oxygen behind the catalytic converter
◦ Amount of H2O in front of the catalytic converter
◦ Amount of oxygen in front of the catalytic converter

[patma1981]

Answer 1

relatively low (close to 0 volt)

Answer 2

Amount of oxygen behind the catalytic converter

[PhilipSeeMore]

Thanks for the timely response, appreciate it

[Mochi]

Great answer, keep it coming