T100 Pickup 4WD V6-180.5 2959cc 3.0L SOHC (3VZ-E) (1993)
Oxygen Sensor: Description and Operation
PURPOSE
The Heated Oxygen Sensor (HO2S) , located at the exhaust pipe with the sensor end extending into the exhaust stream, supplies a voltage signal
to inform the Engine Control Module (ECM) of the air/fuel mixture in the engine.
The Sub Heated Oxygen (SHO2) Sensor is used by the ECM, on California models only, to test the operation of the Catalytic Convertor by
comparing readings between the HO2S and the SHO2 Sensors.
OPERATION
Both the HO2S and SHO2 Sensor use zirconia and platinum to compare exhaust oxygen content with that of the outside air. When heated by the
combination of its internal heater and exhaust gases, the sensor supplies a low voltage signal to the ECM. When the engine is running rich, the
oxygen differential is relatively high so signal voltage increases. When a lean condition occurs the difference in oxygen content is much lower
causing a lower voltage signal to be produced.