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code po440


03gtp
09-19-2010, 07:12 PM
hello all car lovers, i was wondering if i could get some help? i have a 2003 grand prix GTP with a code of po440. it is a code for the evap system. it shows a insuffant vacum leak. i hooked a vacum gauge up and it is holding where it sholud be, and just for giggles i replaced my gas cap. so i'm at a cross road on where to go next. anyone have this problem or any ideas on what it might be? any help would be great, thank you for your time and help!!!

tblake
09-19-2010, 09:19 PM
Welcome to AF!

Did you measure engine vacuum or EVAP system vacuum? And if EVAP system, where did you hook your vacuum guage to? Usually to check for an EVAP leak you need a scan tool capable of commanding the vent and purge soloniods closed, then with a smoke machine you run smoke through the EVAP system using the "EVAP test port" until it starts coming out somewhere.

P0440 = EVAP system Large leak (not insufficient leak)

Good call in replacing the gas cap as the first step. Did you clear the code after replacement?

AutoService101
09-19-2010, 10:32 PM
Most common issue would be vent control valve sticking. (have you smelled fuel from outside vehicle at all and do you ever over fill fuel tank with gas after nozzle clicks off?)
Best to follow tblakes instructions or bring it somewhere to test. Vent control valves is not easy to replace on that vehicle if I am not mistaken.....:screwy:

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