2005 Buick Rendezvous read the code

ALFA-V

MEMBER
2005 BUICK RENDEZVOUS
6 CYL
FWD
AUTOMATIC
76,600 MILES

Hello,
a couple of days ago, my check engine light came ON. On the next gay, another light "missing gas cap" came on too. So now I have to warning lights ON. I borrow it a code reader fron bbody of my and read the code. P0449. I went to the Canadian Tire store and purcesed a new gas cap. Today I resetet-it the two code's with the same code reader. Warning lights went off, however after driving about 25km the check engine light came ON again. What is it? The code the same P0449. What is it exacly wrong, where is locate it and would be possible to correct this isssue without dilership involvment.
Iam mechanicaly savy, just need some info. Thank you in advance.
Victor

1 Reply

BRIAN 1

MECHANIC
1,030 POSTS

P0449 is Evaporative Emission (EVAP) Vent Solenoid Control Circuit. You have to use a scan tool that can command the vent solenoid on/off to see if it clicks, if not you have to have evap system tested with a nitrogen smoke machine to find a possible leak. The SES light came back on because the gas cap was not the problem, driving it 25km allowed the evap system to test itself and there was a leak somewhere. This is not something you can really diagnose without proper equipment and testing.