What is a PO 440 code?
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Cadillac Seville / Cadillac Eldorado Forum Discussion, What is a PO 440 code? in Past Cadillac Vehicle Discussion; Ran my codes recently, got a PO 440 code that is current. Should this be of concern? car is running ...
  1. #1
    92WHTSTS's Avatar
    92WHTSTS is offline Cadillac Owners Fanatic
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    What is a PO 440 code?

    Ran my codes recently, got a PO 440 code that is current. Should this be of concern? car is running great. Only other codes were history, and they were TCS C1225 and C1226, which I believe to be the left front and right front hubs or bearings. Am I correct?

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    JimD is offline Cadillac Owners Connoisseur
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    Re: What is a PO 440 code?

    Quote Originally Posted by 92WHTSTS View Post
    Ran my codes recently, got a PO 440 code that is current. Should this be of concern?
    Yes.
    P0440 - Evaporative Emission (EVAP) System (GAS CAP?)

    Any emission code is (should be) a concern.

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    92WHTSTS's Avatar
    92WHTSTS is offline Cadillac Owners Fanatic
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    Re: What is a PO 440 code?

    Quote Originally Posted by JimD View Post
    Yes.
    P0440 - Evaporative Emission (EVAP) System (GAS CAP?)

    Any emission code is (should be) a concern.
    Haven't had a gas cap error msg on the DIC, so what could this be? Like I said, car is running great.

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: What is a PO 440 code?

    Quote Originally Posted by 92WHTSTS View Post
    Haven't had a gas cap error msg on the DIC, so what could this be? Like I said, car is running great.
    P 0440 is a generic code that says there may be small vacuum leak in the EVAP system - it could be anything from a rusted out fill pipe to a bad vent tube to a bad tank vent solenoid/tubing, bad EVAP charcoal canister, disconnected hose at the EVAP purge solenoid. Time to remove the beauty cover and start tracing hoses. This diagram is for a 2002, but the system is essentially the same as yours. Your EVAP service port has a green cap on the tube near the fuel lines at the firewall in the engine compartm,ent.

    Use this. http://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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    JimD is offline Cadillac Owners Connoisseur
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    Re: What is a PO 440 code?

    Quote Originally Posted by 92WHTSTS View Post
    Haven't had a gas cap error msg on the DIC, so what could this be?
    The code definition includes the "GAS CAP?" terminology as a reminder. Code P0440 can be set by any one of a multitude of failures in the EVAP system ranging from failure of one the two solenoids involved to the plumbing between components.

    If you are 100 percent certain the gas cap is tight (until you feel it ratchet) and the gas cap gaskets are not ruptured, more in depth diagnosis is indicated.

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    92WHTSTS's Avatar
    92WHTSTS is offline Cadillac Owners Fanatic
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    Re: What is a PO 440 code?

    Thanks Sub for the link and Jim for your input as well. Will check it out. Hope it's not something major.

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