I have a RR Sport 2015 with almost 100k miles on it. It runs fine but the engine yellow light came on with Codes P0442 and P0456 on the scanner. I changed the gas cap which helped temporarily. Within a few days the engine light came back on. I went to a local Virginia autoshop and they changed other things I didn't need like all the batteries without fixing the reason I came in for. Is the smoke test the best route to figure out what's actually wrong? The same local autoshop said the smoke test will take 2 hours to complete. Any suggestions?