PO455, PO449 help ?

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Thread: PO455, PO449 help ?

  1. #1
    Walking
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    PO455, PO449 help ?

    My 70,000 mile 2003 Silverado 5.3 has had PO455, and PO449 issues for some time. My local shop suggested I go to a dealer for a smoke test to help identify the problem.

    Since all the Chevrolet dealers within 20 miles have Closed, Today I tried the Buick, Pontiac, Gmc dealer nearby.

    I mentioned at the service counter the fact that I have these two SES codes, and would like to have the smoke test done. I asked the price ( $ 84.00), I also asked if there would be an additional charge to read the codes ( No it's included in the $ 84.00)

    Two hours and NO smoke test later, I was told that I need new intake gaskets, and an Oxygen sensor. ( Since I now have codes, P1133, PO131, PO171, PO455, PO 449, and PO300 )

    They suggested that after I get the $ 850.00 intake gaskets, and the $ 325.00 oxygen sensor, that they clear the codes, and see what comes back on. For another $ 84.00

    They also suggested that I might want to get a smoke test to check the PO455, PO449 ( after the intake gasket fix )

    The intake gasket suggestion was based on the fact that GM has had intake gasket issues, and has developed a new improved part #

    My question, Is this normal operating procedure at a GM dealer ? Or, did I just pick a Bad one ?


    Any suggestions would be appreciated

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    2.8 Liter Turbocharged V6 73ChevelleSS's Avatar
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    Re: PO455, PO449 help ?

    Yes you picked a bad one.You most likely have an issue with the Evap vent solenoid for the P0455,and P0449.The intake gaskets will leak on a cold start.This will cause the P0300(misfire) and the P0171 (lean code).The P1133 and P0131 are O2 sensor codes.I would find a dealer/mechanic that knows what they are doing.There also is a bulletin for the Evap codes to relocate the Evap solenoid to prevent dirt etc from messing it up.
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  4. #3
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    Re: PO455, PO449 help ?

    Thanks

    I called the service manager to see if they actually checked the intake gaskets, with starter fluid , or something . (NO We don't need to check them, they are a frequent problem, That's why the service bulletin tells us to use the new part # )

    They also said I may need all Four O2 sensors. ( Since you should replace the whole set, not just one )

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    Re: PO455, PO449 help ?

    Get a new shop, it is never correct to throw parts at a vehicle without a proper diagnosis.
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    Re: PO455, PO449 help ?

    Agree with the evap vent solenoid diagnosis.

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    Re: PO455, PO449 help ?

    The gaskets on these trucks are a known problem. I just went though an O2 sensor, and it fouled 2 of my plugs, had them replaced. This dealership sounds like a crock...
    It may be very true your intake is bad. But replacing all 4 O2s? that sounds fishy to me.
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  8. #7
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    Re: PO455, PO449 help ?

    Been a few weeks since I replaced the intake gaskets. Most of the time the truck runs great, I still have not done the O2 sensor ( Too much snow on the ground )

    Every few days it goes through a cycle. Very low, rough idle, The SES light comes on for a day, or so, then goes off, and everythings fine again.

    Yesterday I bought a cheap code reader from autozone. I cleared the codes, and drove it again today. Rough idle at stop lights all day.

    I checked the codes again when I got home.

    I have PO131, PO171, PO300, and P1133

    If the PO131, and P1133 are the O2 sensor, What could be causing the PO171, and PO300 again ?

    I had hoped the intake gaskets were causing the PO171, and PO300 ?

    Could the bad O2 sensor be causing the lean condition ?

    Or, Any ideas what else to look for ?

    I am off this weekend, and plan to lay in the snow to do the O2 sensor.

    Any help is greatly appreciated

    Thanks again

  9. #8
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    Re: PO455, PO449 help ?

    I'm not getting the PO455, and PO449.

    Right now anyway

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    Re: PO455, PO449 help ?

    Yes an O2 sensor can cause false codes. The entire fuel strategy of the engine is based upon the O2 readings. If the sensor is stuck lean the engine computer will continue to richen the engine until it determines the O2 is bad. In the mean time the plugs start to foul and miss. Good luck I hope that the O2 is the cause of your woes.
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    Re: PO455, PO449 help ?

    Replaced Bank1 Sensor1 O2 sensor today.

    Still getting PO171 within a few minutes run time.

    After putting a few miles on it I get the PO 171 and PO300

    Clear codes, and PO171 pending comes right back

    Any ideas what to try next ?

    Also changed fuel filter, just because its been about 20,000 miles.

    Sprayed carb cleaner all around New intake gaskets, Throttle body o-ring, all air intake connections ( Nothing )

    Runs great on the highway, Rough / Low idle at a stop light.

    Thanks

  12. #11
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    Re: PO455, PO449 help ?

    Thanks, Haven't had the Evap solenoid done yet, because the code has never came back.

    I guess it's time for another trip to a dealer. Been to 4 different GM dealers so far, and none of them have been able to find the problem.

  13. #12
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    Re: PO455, PO449 help ?

    I dealt with some major issues like this... I ended replacing the fuel pump and transmission because of a computer upgrade fuel pump stayed on to long causing over-reving of the engine and transmission hard shifting.... The engine computer needed to be upgraded... it ran real rough at idle but great on the highway. checked everything and finally found that the fuel pump was jacked causing the issue. Curious to see what you find. It took 8 dealers to finally find the issue.

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