Oxygen Sensor (O2S)
WARNING: This page is about a different car, the 1995 Pontiac Trans Sport, 1995 Oldsmobile Silhouette, and 1995 Chevrolet Lumina APV. However, it is still accessible from the selected car via links, so may be relevant.
See ENGINE SENSORS & SWITCHES .
NOTE:
If injectors are dirty, they should be cleaned using approved injector cleaning procedure before performing port fuel INJECTOR BALANCE TEST.