Sentra L4-1.8L (QG18DE) (2004)
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Oxygen Sensor: Description and Operation
HO2S2 HEATER
Description
System Description
SYSTEM DESCRIPTION
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed, amount of intake air and engine coolant
temperature.
HO2S2
Component Description
The heated oxygen sensor 2, after three way catalyst (manifold), monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1 are shifted, the air-fuel ratio is controlled to stoichiometric, by the signal from the
heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions. Under
normal conditions the heated oxygen sensor 2 is not used for engine control operation.
A/F SENSOR 1 HEATER
Description
System Description
SYSTEM DESCRIPTION
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to the engine operating condition to keep the temperature of A/F
sensor 1 element at the specified range.
A/F SENSOR 1
