OBD II code P0440

I pulled this code today after i started up the rodeo. I forget the specific name, but it had something to do with emission control. I erased the code and since it has not returned. I am expecting it to return soon. Does anyone have any info on what to do when the code returns(what needs to be fixed or cleaned etc) any help would be great.
code was P0440
thanks

luke

EVAP system malfunction, is the what the error code states.

Do you gas up with the car running? If so this will trip this code. If not, check your gas cap (if it is closing properly and is tight), check canister purge valve/ solenoid is working and not leaking, check canister for leaks, check all vacuum lines to these items for leaks.Often, rubber elbows and connectors start to crack and leak. Start off there.

hey thanks for the info...i did gas it up a couple times with the rodeo running, but it didnt trip the code at that time...the code is erased now, so we'll see what happens, if it trips again, than the vacuum lines are next. thanks

On a 1999 rodeo, it's probably just a bad gas cap. The check valve in the cap sometimes stick & allow the tank to fully blow down. You should only be able to suck air thru the cap, not blow air out. A new cap is like $3 at a parts store.
G/luck
Joel