Oxygen Sensor: Description and Operation

DESCRIPTION

The Oxygen Sensors (O2S) are attached to, and protrude into the vehicle exhaust system. Four sensors are used: 2 upstream (referred to as 1/1 and 2/1) and 2 downstream (referred to as 1/2 and 2/2).

The upstream sensors (1/1 and 2/1) are located in the exhaust of the cylinder bank just before the catalytic converter. The downstream sensors (1/2 and 2/2) are located in the exhaust downpipe of the cylinder bank just after the catalytic converter.