Oxygen Sensor: Description and Operation

Sensor Cutaway:

Reference:

Heated Oxygen Sensor (H02S)-1 and -2
The oxygen sensor-i is installed on the exhaust manifold (pre- catalyst) and the oxygen sensor-2 is installed on the exhaust pipe (post-catalyst). Each sensor detect the concentration of oxygen in the exhaust gases.
ECM (PC M) detects the air-fuel ratio of the mixture supplied to the engine by monitoring the signal (output voltage) from sensor-i. The signal (output voltage) from sensor-2 is used to detect malfunction of the three way catalytic converter. Each oxygen sensor heater promotes activation of the oxygen sensor.





HEATED OXYGEN SENSOR HEATER (SENSOR-1 AND SENSOR-2) CONTROL SYSTEM
This system controls operation (ON/OFF) of each heater which assists activation of each oxygen sensor. ECM (PCM) turns the each heater of oxygen sensor-1 and -2 ON (to allow the electric current to flow to the oxygen sensor heater) when the engine is running without high-load condition after specified time from engine start.