AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) CONSTRUCTION/OPERATION [ZJ, ZY]
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A/F Sensor
• Installed to the exhaust manifold.
• A zirconia element-type sensor (all-range air/fuel ratio) has been adopted.
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― All-range air/fuel ratio sensor
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• Utilizes a characteristic in which the electrical current fluctuates minutely according to the size of the air/fuel ratio (remaining oxygen concentration).
• The air/fuel ratio outputs minute values in the rich-to-lean range to enable fine monitoring of the degree to which the air/fuel ratio is rich or lean.
• Electrical current is output based on the oxygen concentration in the exhaust gas.
HO2S
• Installed to the exhaust gas manifold.
• A zirconia element-type sensor (theoretical air/fuel ratio sensor) has been adopted.
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― Theoretical air/fuel ratio sensor
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• Utilizes the characteristic in which the voltage changes significantly at the border of the theoretical air/fuel ratio (A/F = 14.7).
• The size (remaining oxygen concentration) of the air/fuel ratio in relation to the theoretical air/fuel ratio is determined by how small (rich) or how large (lean) the air/fuel ratio is.
• Voltage is output based on oxygen concentration in the exhaust gas.
A/F Sensor Heater, HO2S Heater
• A heater element is integrated so that electromotive force does not occur while the zirconia element temperature is low (after cold-engine starts). The heater warms the sensor which promotes activation of the sensor and stabilizes its output.
