Oxygen Sensor (O2S)
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 1996 GMC Yukon, 1996 GMC Vandura Special, 1996 GMC Vandura, 1996 GMC Suburban, and 1996 GMC Savana Special. 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.