Oxygen Sensor I and II

Oxygen Sensor (Three-Wire Type):

Oxygen Sensor With Internal Heater:

PURPOSE AND LOCATION
Oxygen Sensor I
The oxygen sensor I (G3/2), located in the exhaust system upstream of the catalytic converter, is used to provide more precise control of air/fuel mixtures.

Oxygen Sensor II
The oxygen sensor II (G3/1), located in the exhaust system after the catalytic converter, is used to provide a monitoring signal to the diagnostic module.

OPERATION
This system operates by measuring oxygen content in exhaust gases, as the amount of oxygen remaining in the exhaust gas is directly proportional to the air/fuel ratio of mixtures entering the engine. The sensor, mounted in the exhaust stream, reacts to the oxygen remaining in the exhaust gases and produces a variable voltage signal (0.4 - 1.0 VDC) depending upon the oxygen content.

Oxygen Sensor Voltage:

SIGNAL
A rich mixture will produce a high voltage (up to 1.0V) and a lean mixture will produce a lower voltage. Oxygen sensor I sends the signal to the HFM-SFI control module. Oxygen sensor II sends the signal to the diagnostic module.