1997 Buick Century

Engine Performance problem
1997 Buick Century 6 cyl Front Wheel Drive Automatic 169505 miles

diagnostic code shows PO440
February 16, 2009.

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P0440 Evaporative Emission Control System Malfunction

This code normally appears if the driver forgets to put the gas cap back on, or the gas cap seal is bad. Double check the vacuum line from the throttle body to the purge solenoid for leaks. The best way is with a smoke machine. There could also be an issue with the purge solenoid or the electrical connection to it.

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Feb 16, 2009.
P0440 EVAP System No Flow During Purge Possible Causes Setting Conditions

Charcoal canister is loaded with fuel or moisture
Fuel filler cap is loose, cross-threaded, damaged or wrong part
Fuel tank, fuel filler neck or fuel sending unit 'O' ring is leaking
Fuel tank pressure sensor is damaged, disconnected or it failed
Fuel tank vapor line(s) is clogged, damaged or disconnected
Purge valve vapor line is clogged, damaged, or disconnected
Purge or vent solenoid power circuit is open (check the fuse)
PCM has failed

Feb 16, 2009.