AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION [L5]

AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION [L5]SM1934838

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Pre-heater Control (A/F sensor Heater)

Operation condition

• From the engine start to the threshold time: The PCM supplies voltage of approx. 3.5 V.

Cycle Estimated Control

A/F sensor heater

Operation condition

• The PCM operates the A/F sensor heater according to engine operation conditions as shown in the table below.

Drive duty ratio	Engine operation conditions
0 %	• Ignition off • Engine is stopped • At engine start (cranking)
Approx. 50 % (Determines the duty ratio by measuring the element temperature with the A/F sensor heater element impedance)	• After engine warm up (duty ratio varies according to battery condition)

HO2S heater

Operation condition

• The PCM operates the HO2S heater according to engine operation conditions as shown in the table below.

Drive duty ratio	Engine operation conditions
0 %	• Ignition off • Engine is stopped • Within a fixed period of time after engine start (time varies according to engine coolant temperature) • Engine speed is 4,250 rpm or more • Charging efficiency is at the set value or more (charging efficiency varies according to engine speed)
30 %	• Drive duty ratio is other than 0 % or 100 %
100 %	• During KOEO self test execution