Maybe some of you car-savvy forum members can me figure this out. I recently had the oil changed in my 2003 Hyundai Accent, and the next day my amber Check Engine light came on and stayed on. I had AutoZone scan the computer and they came up with a P1401 code, which indicates some sort of fuel system pressure problem. They said that it's frequently caused by a failing O-ring on an old gas cap. So I replaced the gas cap with a new one, disconnected/reconnected the battery to clear out the codes, and everything was fine for about 3 days -- and then the CEL came on again. I assume this means I'll end up buying a new purge solenoid, hose or hose clamp, fuel pressure sensor or who knows what else. But what I can't understand is -- why would my gas-cap fix seem to solve the problem for 3 days if the problem lies elsewhere? I'll have to get this fixed by end of November or I'll most likely fail my state inspection. Drat.