I had the P0442 (If my memory is correct) evap system engine code for MONTHS trying to figure out what was going on. The evap canister valve wasn't able to open, allowing regulation of evap vapor pressure. This caused the gas tank to overflow every time I was at the pump; unless I were to pull the handle on the pump veeery lightly. my mechanic bro hooked up the smoke test and we determined it was a vapor leak coming from the top of the gas tank, near the pump. I opened the hatch behind the back passenger side seat, in the trunk, to expose the tank. The way that the lock ring holds onto the brittle plastic fuel pump's flanged top causes it to crack & break, messing up the vapor pressure sensors in the evap system. This mucks up the oxygen/fuel ratio. I KNOW this is a common problem with the Sonatas, because when I eventually ordered a fuel pump from Ebay, the one in the mail had the same exact problem!! ( I noticed this while trying to install it).
Overall, it's a pain in the ass, but if you have this car, and you get ANY evap code, check the fuel pump. Easiest way to do it is open the hatch behind the back seat and hook it up to a smoke tester. (If your mechanic charges you more than 40 bucks for this, tell them to screw off). I hope this helps anyone in this predicament, because it took me a long time to figure it out.
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I had the P0442 (If my memory is correct) evap system engine code for MONTHS trying to figure out what was going on. The evap canister valve wasn't able to open, allowing regulation of evap vapor pressure. This caused the gas tank to overflow every time I was at the pump; unless I were to pull the handle on the pump veeery lightly. my mechanic bro hooked up the smoke test and we determined it was a vapor leak coming from the top of the gas tank, near the pump. I opened the hatch behind the back passenger side seat, in the trunk, to expose the tank. The way that the lock ring holds onto the brittle plastic fuel pump's flanged top causes it to crack & break, messing up the vapor pressure sensors in the evap system. This mucks up the oxygen/fuel ratio. I KNOW this is a common problem with the Sonatas, because when I eventually ordered a fuel pump from Ebay, the one in the mail had the same exact problem!! ( I noticed this while trying to install it).
Overall, it's a pain in the ass, but if you have this car, and you get ANY evap code, check the fuel pump. Easiest way to do it is open the hatch behind the back seat and hook it up to a smoke tester. (If your mechanic charges you more than 40 bucks for this, tell them to screw off). I hope this helps anyone in this predicament, because it took me a long time to figure it out.
- Benjamin M., Portsmouth, NH, US