CONTROL SYSTEM
01–40–32
HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OUTLINE [LF]
E5U014000000N40
• Stabilized oxygen concentrations, even when the exhaust gas temperature is low, are detected by controlling of
the HO2S, enabling feedback control of the fuel injection control even during cold-engine starting, improving
emission performance when cold.
• When the exhaust gas temperature is high, the HO2S is protected from sharp rises in its temperature by
stopping energization to the HO2S heater.
• Emission performance improvement and protection of the HO2S have both been achieved by the duty control
of the front and rear HO2S according to the engine operation conditions (exhaust gas temperature).
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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL BLOCK DIAGRAM [LF]
E5U014000000N41
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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION [LF]
E5U014000000N42
Operation Conditions
• The PCM operates the HO2S when the following conditions are met.
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PCM
ECT SENSOR
IAT SENSOR
CKP SENSOR
TP SENSOR NO.1, NO.2
MAF SENSOR
MAP SENSOR
BARO SENSOR
REAR HO2S HEATER
FRONT HO2S HEATER
BATTERY
E5U140ZW5402
HO2S Activation condition Drive signal
Front
• After engine start
• After the engine has started and a fixed period
of time has elapsed (the elapsed time period
after the engine starts is determined by ECT).
• ECT is –10 °C {14 °F} or more.
• Battery positive voltage is 9 V or more and less
than 16 V.
• MAF sensor is normal (no DTC is stored in
PCM).
• The PCM outputs a duty signal.
• The element temperature is measured by the
impedance of the HO2S and a duty ratio is
determined.
Rear
• Starter is off
• After engine start
• After the engine has started and a fixed period
of time has elapsed (the time period after the
engine starts lengthen if the ECT falls below
0°C {32°F}.
• ECT is –10 °C {14 °F} or more.
• Battery positive voltage is 9 V or more and less
than 16 V.
• Charging efficiency is the fixed value or less, or
during fuel cut.
• The PCM outputs a duty signal.
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