GMC 2010 Sierra 1500 Crew Cab Owner's Manual page 268

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.
Some state/provincial and 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.
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The vehicle may not pass inspection if:
the check engine light 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.
the critical emission control systems have not been
completely diagnosed by the system. This can
happen if the battery has recently been replaced or
if the battery has run down. The diagnostic system
evaluates critical emission control systems during
normal driving. This can take several days of
routine driving. If this has been done and the
vehicle still does not pass the inspection, your
dealer can prepare the vehicle for inspection.