I replaced the gas cap and the code still comes back When I clear it the code goes away but the scanner keeps a yellow light and most diagniose don`t complete
I keep getting a PO440 code on my obd2 on 2001 Hyundai Elantra
you may have several issues,poss vac leak,sensor or purge issue. seek a diag and est and don't guess it could get pricey
Are you using a 'code reader' or a real scanner? Readiness codes need to go through specific conditions or drive cycles to 'complete' will stay 'yellow as long as any item that applies is not 'complete'. Suggestion - get it diagnosed as globalhelper suggested , keep your fumes in your own tank. Once it's fixed and the code is cleared , it may take several days and a few hundred miles of driving to get all readiness codes 'complete' depending on driving style and conditions , but each time the codes are cleared (or reset) you must go through the driving all over again. Patience.good luck.
you need an evap diagnosis...somehow fumes are not being held in your gas tank