I think gas-cap tightness sensors are pretty common, possibly mandatory? My 2004 hyundai accent, probably the cheapest car you could get in NA in that time, thr

I think gas-cap tightness sensors are pretty common, possibly mandatory? My 2004 hyundai accent, probably the cheapest car you could get in NA in that time, throws a CEL if you don't tighten the gas cap past 3 clicks or so, it's even documented in the user manual.