My engine light came on but after I filled tires it went out still did diagnostic check P0316 and P0302 showed what are they and how much should it cost?

P0316 is misfires detected in the first 1000 crank revolutions after start-up, so that means the computer was detecting misfires in the first 30 seconds or so after a cold start. The P0302 is a misfire detected in cylinder #2 and that would have to be diagnosed.