Heated Oxygen (HO2S) Sensor

HO2S is mounted in exhaust manifold in front of 3-way catalytic converter. HO2S produces .1-.9 volts under normal operating temperatures greater than 600°F (316°C). ECM uses HO2S 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 works similar to a non-heated sensor, except HO2S is heated to operating temperatures during engine operation.