Skylark L4-144 2.4L DOHC VIN T SFI (1997)
Oxygen Sensor: Description and Operation
Rear Heated Oxygen (HO2S 2) Sensor
Description
The Rear Heated Oxygen Sensor (HO2S 2) is used to monitor the oxygen storage capability of the catalytic converter. Similar to the 02S 1, the H02S 2
reacts with the oxygen content in the exhaust stream to produce a voltage signal, only after the catalytic converter.
Operation
This voltage ranges from approximately 0.1 volt (high oxygen - lean mixture) to 0.9 volt (low oxygen - rich mixture). Unlike the 02S 1, with a good
catalytic converter, the H02S 2 is normal when its activity appears lazy or inactive. The PCM compares readings from both the front 02S 1 and the
HO2S 2 to determine the catalyst efficiency and will illuminate the Malfunction Indicator Lamp (MIL) if this efficiency falls below a calibrated level.
