MX-3 L4-1597cc 1.6L (1992)
Oxygen Sensor Output Voltage vs. Air/Fuel Ratio
PURPOSE
Measures oxygen content of exhaust gas and sends a voltage signal to the ECU. The ECU determines air/fuel ratio based on sensor voltage signal
and makes appropriate adjustments to maintain the optimum ratio for prevailing operating conditions.
LOCATION
Exhaust manifold.
OPERATION
Oxygen reacts with the platinum surfaces when the temperature is high. When there is a difference in the amount of oxygen reacting with the inner
and outer surfaces, a voltage potential is generated. The voltage range is approximately 0.1 - 1.0V. Voltage increases when the concentration of
oxygen in the exhaust is low (rich air/fuel ratio) and decreases when the concentration is high (lean air/fuel ratio). The difference in oxygen
concentration in the narrow range of optimum air/fuel ratio causes a large voltage change that is easily measured by the ECU. The sensor element
only reacts efficiently with oxygen if the temperature of the element is around 575°F (300°C) or hotter.
CONSTRUCTION
Sensor consists of a hollow Zirconia element with a Platinum coating on its inside and outside surfaces. The open end is exposed to the
atmosphere and its surface is connected to the ECU. The closed end protrudes into the exhaust stream and its surface is connected to ground.
