check engine lite on where is cannsiter located on this car and can I fix 21146

What started this was I had valve cover gaskets replaced and noticed engine lite came on shop put on computer and they found some problems in engine area and fixed Day later on again this time shop said P ?? code that was charcoal canister and maybe that was problem. So I need to take back next week just when I paln to sell car thsi happens So I was wondering if ti could be clogged line to canister or something small I can fix? thanks

DEPENDS ON CODE. COULD BE A HOSE LEAK. A FUEL SENDING UNIT LEAK OR A NUMBER OF SENSORS NOT WORKING PROPERLY

thanks for your time..I was thinking of looking at the canister over the weekend to see if all connections are good, any holes clogged anything else I can do if I can see the cansiter once I jack up the car?