Suzuki DF150 Service Manual page 74

ENGINE CONTROL SYSTEM 3-15
O2 SENSOR (Optional item)
The O2 sensor is installed in the exhaust manifold only when the
Zirconia element
O2 feedback operation is performed.
This sensor is a zirconia element (platinum plated) which Housing
changes output voltage depending on the oxygen concentration
difference between its internal and external surfaces. The volt-
age change reflects the concentration of the oxygen in the
exhaust gas and is used to perform the O2 feedback operation.
The terminal voltage change (0 – 1 V) is dependent on the con-
centration of oxygen in the exhaust gas.
This detected voltage value therefore represents the oxygen
concentration. The terminal voltage decreases when the oxygen
concentration is high, and increases when it is low.
NOTE:
As the Zirconia element is not conductive below 250 °C, the O2
sensor will not function properly until the engine is at normal
operating temperature.
NOTE:
Zirconia element:
The zirconia element produces a potential difference (voltage)
when there is a difference in the oxygen concentration of the
gases which contact the two sides of the element.
Since the inner surface of the Zirconia element (inside the sen-
sor) is exposed to atmospheric air and the outer surface
exposed to the exhaust gas, there is a difference in oxygen con-
centration on each side and thus a difference in the potential
generated.