Trouble Code

My 2000 LS1 , 79K miles, 4 cycl. turned on the check engine light today. I
borrowed a scanner and pulled the code p0440.

The report I got states that this is an Evaporative Emission Control System
Malfunction... aka the charcoal canister. It states that this code could be
caused by a bad sensor, solenoid, actuator or a related solenoid, actuator
or sensor.In other words just about anything connected or remotely related
to the canister oculd be causing the error.

Has anyone else had this code pop up and if so, what did you find to be the
end cause? I don't have the time or funds to run down the list of
possibilites mentioned in the report to eliminate the problem nor can I
afford the dealerships costs to do the same.

Any help would be appreciated.
Thanks in advance.

 

Oppie has had experience with this very problem IIRC. He should have an
idea of where you should look first.

 

Hello - I had a P0495 (iirc) Large leak, charcoal canister on my 2001 LW300.
Turned out to be the vent solenoid which was mounted aft of the fuel filler
neck.

If your system follows the same diagnostic process, the test goes something
like this.
(disclaimer - this is from memory) Test performed when outside temperature
is above 80F and engine is warmed up.
normal operation is that vent solenoid is open. At engine start, Purge
solenoid opens and modulates to control air flow to purge the canister.
Canister test will close the vent solenoid and open the purge solenoid. A
vacuum sensor mounted on the fuel tank (similar to the MAP sensor) monitors
an increasing vacuum. At some point, the vacuum is judged to be sufficient
(not sure what the "Hg value is) and the purge solenoid closes. You now have
a sealed system and there should be no leak. The tank mounted vacuum sensor
monitors the decay of vacuum and judges whether it is a small or large leak
which sets the corresponding code.

De-energized state of solenoids: vent=open, purge=closed
note - if you utilize the evap system test port, use only air pressure of
3psi MAX. I did so with my air compressor regulator turned WAY down. You do
not want to rupture the tank or components. I have an old R12 air
conditioning manifold valve which made for easy testing with the valves and
compound gauge.

Hope that helped - Oppie