GMC 2012 Sierra - Manual (Page 162)

Black plate (24,1) GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
5-24 Instruments and Controls
The following may correct an
emission system malfunction:
. Check that the fuel cap is fully
installed. See Filling the Tank on
page 9‑72. The diagnostic
system can determine if the
fuel cap has been left off or
improperly installed. A loose or
missing fuel cap allows fuel to
evaporate into the atmosphere.
A few driving trips with the cap
properly installed should turn the
light off.
. Check that good quality fuel is
used. Poor fuel quality causes
the engine not to run as
efficiently as designed and may
cause stalling after start-up,
stalling when the vehicle is
changed into gear, misfiring,
hesitation on acceleration,
or stumbling on acceleration.
These conditions might go away
once the engine is warmed up.
If one or more of these conditions
occurs, change the fuel brand used.
It will require at least one full tank of
the proper fuel to turn the light off.
See Recommended Fuel on
page 9‑68.
If none of the above have made
the light turn off, your dealer can
check the vehicle. The dealer has
the proper test equipment and
diagnostic tools to fix any
mechanical or electrical problems
that might have developed.
Emissions Inspection and
Maintenance Programs
Some local governments may have
programs to inspect the on-vehicle
emission control equipment. For
the inspection, the emission system
test equipment is connected
to the vehicle’s Data Link
Connector (DLC).
The DLC is under the instrument
panel to the left of the steering
wheel. See your dealer if assistance
is needed.
The vehicle may not pass
inspection if:
. The malfunction indicator lamp is
on with the engine running, or if
the light does not come on when
the ignition is turned to ON/RUN
while the engine is off. See
your dealer for assistance in
verifying proper operation of the
malfunction indicator lamp.
. The OBD II (On-Board
Diagnostics) system
determines that critical
emission control systems have
not been completely diagnosed.