Trouble Code

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- <drd6800
  
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posted
18 years ago

Tue, Sep 6, 2005 5:38 PM

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.

-- Pat 2000 LS1

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- blah blah
  
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posted
18 years ago

Tue, Sep 6, 2005 7:14 PM

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- Oppie
  
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posted
18 years ago

Wed, Sep 7, 2005 1:32 PM

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