Question

2002 GMC Sierra 5.3L V8 with engine code P0449, will this affect performance?

Answer 1

P0449 GMC - Evaporative Emission Vent Valve Solenoid Malfunction

Read more: https://www.autocodes.com/p0449_gmc.html

Start by checking the fuel cap and if the cap is OK the next step is to check for vacuum leak. If no leak are found you may have to replaced the EVAP Vent Control Valve.

Any problems related to the the EVAP system should not affect then engine performance.