ENGINE CONTROL SYSTEM 3-10
O
2
SENSOR (Optional item)
The O
2
sensor is installed in the exhaust manifold only when
the O
2
feedback operation is performed.
This sensor is a zirconia element (platinum plated) the output
voltage of which changes depending on the oxygen concen-
tration. The voltage change reflects the concentration of the
oxygen in the exhaust gas and is used to perform the O
2
feed-
back operation.
The terminal voltage change (0 – 1 V) is dependent on the
concentration of oxygen in the exhaust gas.
This detected voltage value therefore represents the oxygen
concentration. The terminal voltage decreases when the oxy-
gen concentration is high, and increases when it is low.
NOTE:
As the zirconia element is not conductive below 250°C, the O
2
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 ex-
posed to the exhaust gas, there is a difference in oxygen con-
centration on each side and thus a difference in the potential
generated.
Zirconia element
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