Your smog technician is correct. The catalyst monitor, the evaporative
monitor, and the EGR system monitor need to be complete in order for your
Chevy to pass the smog check. Setting the monitors does require driving your
C-1500 at least 100 miles. We recommend 200 miles; consisting of everyday
normal driving, stop and starts (like at red lights and traffic), ignition
on and off several times a day with at least 15 minute pauses in between
(this allows the EVAP monitor to run), and freeway driving at least on three
occasions for at least 15 minutes each at speeds above 30 mph.
With this all said done, and your Chevy still failing the OBD II portion of
the smog check which checks for incomplete or completed monitors, we can
only recommend a smog check repair center conduct a diagnosis of the truck's
OBD II computer as to clues of why the monitors are not setting.
Assuming no Check Engine light or Malfunction Indicator Lamp is illuminated
we have to suspect your truck's only problem here is simply not enough drive
time yet.
