[MrStang123]

My bro's 97 Maxima's check engine light has been coming on. And the codes it gave were the knock sensor, o2 sensor and something like EVAP (evaporative emission system) purge/vent solenoid circuit condition. The mechanic said that maybe my gas cap is faulty and is causing the knock and Evap to go off. Does this seem likely? Car has 108k miles.

[timeless2]

It's a safe and cheap thing to try, but if you were throwing O2 codes (something upstream), I am inclined to believe it's something aside from the fuel tank cap.