OK so my check engine light turned on last night [:@]I took it to autozone this monrning and heres the code P1456... the definition is EVAP emission control system leak detected (fuel tank system).. The probable causes 1. loose fuel cap 2. vapor canister saturated 3. Failed vent solenoid 4. failed purge solenoid...

anyone know how to fix this or where exactlly i should be looking at? thanks

 

All you can do is perform a visual check of all routed hoses, connectors, etc that pertain to the EVAP system. From the fuel tank all the way up to the motor. If you don't find anything obvious, and you don't have a scan too or the diagnostic procedure, you might as well just take it to a qualified tech cause you'd be guessing.
I have customers that get this code all the time, and they come to me, I can't find a problem with the car at all. Turns out after lots of questions that they leave their car running when they fill up their tank. That was the problem. But they still come back for the same reason, but just to clear the code. So that may or may not be your issue also.

 

ok so my mom's car had the same problem i think and she took it to a mechanic and he quoted the job for $430 he said"she left the car on while refueling and air is stuck in the fuel line" does that sound right?

 

WOW. I sure hope you didn't pay him to fix it!! Air doesn't get stuck in the fuel lines, if that was the case the car wouldn't run or run very poorly.

Basically there is a pressure sensor in the fuel tank, the ECM(computer) reads this sensor constantly, if the ECM see's a dramatic pressure difference suddenly(taking your gas cap off with the car running) it sets this code, amoung others possibly. If this IS your problem, then all you would have to do is clear the code and stop the engine when you fill up from now on.
But there is no air the will be sucked into the fuel line at all from just taking the fuel cap off while engine is running, they just figured your mom for a sucker.

 

As mentioned, start simple. First clear code from ECU. Check that the gas cap is tight. Inspect the rubber seal on the gas cap -- it may be bad. if so, replace the cap.