Oxygen Sensor 1 (O2S 1)

O2S 1 is mounted in exhaust manifold or exhaust pipe in front of warm-up 3-way catalytic converter (WU-TWC). O2S 1 generates voltage according to oxygen content in exhaust gases. Voltage will vary from 0.1 volt (lean condition) to as high as 0.9 volt (rich condition).

Sensor will not generate a voltage signal until it reaches an operating temperature greater than 600°F (316°C). Sensor sends voltage signal to PCM, which uses it to obtain correct emissions by adjusting air/fuel ratio. Until sensor is warmed up, PCM adjusts air/fuel mixture based upon preprogrammed PCM memory (open loop operation).