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Thread: 2002 745i codes P0492 and P0491

  1. #1
    Join Date
    May 2010
    Location
    bethesda, md usa
    Posts
    1
    My Cars
    2002 bmw 745i

    2002 745i codes P0492 and P0491

    i had my alternator replaced and since have had to reset almost daily these codes. is there a fuse under the driver or passenger seat on the e65? the vac lines look fine, it had always had some hesitation at low speed but it is now worse.

  2. #2
    Join Date
    Jun 2008
    Location
    Greensboro, NC
    Posts
    259
    My Cars
    98 M3 Coupe
    assuming these are lean mixture codes or something?


    if youre resetting them daily then something is not right. the only vacuum lines on your engine are from the vacuum pump to the booster and one little on under the intake boot and neither really doesnt sets a fault if theyre open since theyve nothing to do with engine vacuum.

    youve got a problem elsewhere.
    98 Alpinweiss M3: Dinan CAI, HFM, Big Bore throttle kit, exhaust and Stage 4 software, short shifter, shiny long tube headers, koni, H&R HP#'s unknown...

  3. #3
    Join Date
    Jul 2010
    Location
    Saint Marys, Ohio
    Posts
    8
    My Cars
    2007 750Li
    Hey wdsprofess, when you had your alternator replaced how much did it cost you ?

  4. #4
    Join Date
    Oct 2009
    Location
    tampa, fl
    Posts
    36
    My Cars
    300c, 745i, 650i
    Those codes are for your secondary air pump which is located on the passenger side of the car. Hoses run under intake manifold. If both codes are showing then your pump is not functiong correctly right now.

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