Oxygen Sensor: Description and Operation

UPSTREAM HEATED OXYGEN (HO2S) SENSOR:

- Has the ability to create a voltage signal dependent on exhaust oxygen content.
- Provides feedback information to the PCM used to calculate fuel delivery.
- Is positioned in the exhaust manifold outlet.

DOWNSTREAM HEATED OXYGEN (HO2S) SENSOR:

- Monitors oxygen content after the catalytic converter.
- Provides a voltage to the PCM used to calculate catalytic converter integrity.
- Is also referred to as the Catalyst Monitor Sensor (CMS).