Heated Oxygen Sensor 1 (HO2S 1)

HO2S 1 is mounted in exhaust manifold in front of warm-up 3-way catalytic converter (WU-TWC). HO2S 1 produces 100-900 mV under normal operating temperatures greater than 600°F (316°C). When HO2S 1 is cold, normal voltage is 1275 mV. PCM uses HO2S 1 voltage to determine exhaust gas oxygen concentration during engine operation. Low voltage indicates a lean exhaust mixture and a higher voltage indicates a rich exhaust mixture. HO2S 1 works similar to a non-heated sensor, except HO2S 1 is heated to operating temperatures during engine operation.