Sunfire L4-138 2.3L DOHC VIN D MFI (1995)
Oxygen Sensor: Testing and Inspection
Catalyst Monitor Oxygen Sensors
SCAN TOOL TESTING
The Rear Heated Oxygen Sensor (HO2S 2) is used on California vehicles only and is used to monitor the oxygen storage capability of the catalytic
converter. Similar to the O2S, the HO2S 2 reacts with the oxygen content in the exhaust stream to produce a voltage signal only after the catalytic
converter. Unlike the O2S, the HO2S 2 is normal when it's activity appears lazy or inactive. A scan tool can be used to diagnose the HO2S 2 but
should be replaced only when directed to by a diagnostic chart. See: Computers and Control Systems/Testing and Inspection
