V90 L6-2.9L VIN 96 B6304S (1998)
Oxygen Sensor: Description and Operation
Rear Heated Oxygen Sensor
The rear heated oxygen sensor (HO2S) is located downstream of the three-way catalytic converter (TWC) which measures the oxygen content of
exhaust gases there.
This is to:
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provide more accurate fuel trim
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check for aging in the front heated oxygen sensor
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check that the three-way catalytic converter is working.
