A high O2 IS a high oxy reading. and that means a exh leak. O2=oxy.
HC is unburned gas
CO is a product of combuston.
All true!
While a high O2 content indicates high oxygen it will show as a lower reading in volts from the O2 sensor (lean) and will show higher voltage readings during rich conditions. For example, as with an OBD II system the O2 sensors downstream of the Cat will read about 0.0-0.1 volts DC (with a properly functioning Cat) which is normal since the Cat will convert spent gases to mostly Oxygen and CO2 and the front O2 sensors will determine fuel ratio changes. High readings will be from 0.5 to 1.0 volts DC (rich), low voltage readings will be from 0.0-0.4 volts DC (lean).
