Trouble OBD II code P0449 refers your Chevy Silverado's evaporative emission
control system vent valve or solenoid circuit. Trouble code P0449 can be
caused by something as simple as a loose gas cap. We'd recommend filling a
full tank of fuel and ensuring your gas cap is screwed on tight.
If in fact the problem was a loose gas cap, this trouble code should
disappear within a weeks worth of everyday driving. If OBD II P0449 does not
clear, the problem might be due to defective or loose EVAP vent solenoid
connector or perhaps a defective vent solenoid itself.
Try our recommendation of filling up and tightening your gas cap, if the
code reappears you may need a smog check repair station to replace the EVAP
vent solenoid. The vent solenoid (also known as EVAP vent valve) on your
Chevy Silverado should be located at the charcoal canister near your Chevy's
fuel tank. An aftermarket vent valve can be found for as low as $30.00 from
an auto part store, and should be able to be replaced without much effort;
although we do recommend a professional smog check repair station conduct
the repair and resetting of the trouble code.