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2005 Chevy Impala Diagnostic P0440 Code

ffmikemffmikem Posts: 1
edited July 2014 in Chevrolet

My Check Engine Light is on, and I went to autozone and they said it was code P0455, and they said to try the gas cap. I replaced the gas cap, but the light is still on. Will the light go out by itself after I replaced it, or do I have to use the diagnostic tool to reset it? What else would typically cause this code?



  • did you clear the code after installing the new gas cap? it wont just go away by itself until a few cycles.

    -another thing that could cause this code is an evap leak. see here:
  • Hi
    I have a 2005 Chevy Impala, and just recently (now that it's getting cold out) found that the driver's side does not get warm air if I put the heat on. The passenger side does, but, since it's going to be getting cold here in New England soon, anybody have any suggestions as to a possible easy fix?

    Stephanie Kearns
  • I live in Canada and about a month ago same thing started with my car. Then it would only heat up after about an hour, fan blowing cold then warm, then both sides cold, and 2 days ago the light came on to add coolant. I did and made it home but not sure if the same old 2003 story with Impalas is happening (head gasket) but local mechanic ordered a thermostat but will check to see if it is something worse. Sounds like it is a mfg. defect. I do a lot of highway driving and never had trouble with this car until later this summer. It was warm then so I wasn't too worried, but now that the light came on, it can be very costly.
  • romarcromarc Posts: 1
    I have a 2005 Chevy Impala and I am having the same problem as others with the check engine light coming on and staying on. The error code says there is a vacuum leak. I replaced the gas cap and for a shosrt time the light went out, but, it came back on and has stayed on for months now. Does anyone have an answer to resolve this problem? Why doesn't GMC take responsablity for there mistakes like we have to in our personal lives and on the job?
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