Outline Of Diagnosis
WARNING: This page is about a different car, the 2006 Subaru Outback. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
For the diagnostic procedure, refer to
DTC P0140 O2 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 1 SENSOR2) , Diagnostic Trouble Code (DTC) Detecting Criteria.