What would cause a 97 Pontiac sunfire to use more gas than normal and also auto zone codes p1441 and p1621?

P1441 Evaporative Emission System Flow During Non-Purge. P1621 PCM Memory Performance Take this car to a professional as this is going to take some skill and knowledge to repair. Do not throw parts at the problem. here's where you can find out what the codes mean; http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm This is interesting. I assume the original poster's warning lights were on, but can there be issues for which a code is generated but nothing lights up on the dashboard? I think I'm using a lot of gas in my 2003 2.2L but I don't have any warning lights on. Phil I think the two codes being returned have a system in common - the vacuum system/Evaporative recovery system. Evap. (vapor cannister) code MAY be as a result of excessive fuel flow into the cylinders overloading the cannister's capacity. Possible cause is a failing Oxygen sensor giving a "Lean" indication to the engine computer, causing more fuel than is needed to be injected into the cylinders and captured by the vapor system. Trying to keep track of the changing readings may be taxing the computer's memory. Have the oxygen sensor checked. If it is functioning correctly, check for vacuum leaks, cracked or broken vacuum hoses.