PO174 returns for an encore
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Cadillac STS Forum - 2005 through 2012 Discussion, PO174 returns for an encore in Past Cadillac Vehicle Discussion; I celebrated too early, it seems. Got the CEL on the way home last night, checked it after pulling into ...
  1. #1
    mckellyb is offline Cadillac Owners Enthusiast
    Automobile(s): 2005 STS N*, 1SF, 130K mi.
    Join Date
    Apr 2011
    Location
    Fort Worth
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    558

    PO174 returns for an encore

    I celebrated too early, it seems.

    Got the CEL on the way home last night, checked it after pulling into the garage...no codes.

    Whut?

    Put the code reader in the console, in case it happens again. Sho-nuff, it fired off another PO174 this AM.

    Are there any vacuum hoses attached to the airbox which are below it? That's the only thing I can think of, now, though I did put a K&N in there, added no oil. I've done this on multiple modern cars, without issue.

    I tried to get to the MAF, but was dying in the heat before I could get the intake tube off the engine side of the airbox so I could reach it. It's likely just stuck from heat cycling, but I don't want to break anything.

    Ideas?

    I'll check when I get home to see if I kept the old filter...don't think I did..., swap it out and see if that changes the behavior.

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  3. #2
    BaTu is offline Cadillac Owners Enthusiast
    Automobile(s): '05 STS4
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    643

    Re: PO174 returns for an encore

    I didn't find the original post on this (other than the "Yay" one) but, I assume you've checked the intake plenum bolts....?

  4. #3
    mckellyb is offline Cadillac Owners Enthusiast
    Automobile(s): 2005 STS N*, 1SF, 130K mi.
    Join Date
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    Location
    Fort Worth
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    558
    Thread Starter

    Re: PO174 returns for an encore

    Yep, tightened those a few months back, but I should check again. I don't put the engine cover back on, so it'll be quick to do. I'd rather see even an ugly intake vs. a plastic cover, but that doesn't appeal to everyone.

    I'm going to have to take all of the intake plumbing out and look at it...make certain I didn't manage to put a tiny hole in the tubing, somewhere.

    I did put a K&N filter, a drop-in, in there, and that's only the second time the air box has been opened by me. The first was to merely check on the condition of the paper filter when I purchased it. Didn't disconnect anything to do that, just unscrewed the box halves, but the new filter required I loosen the engine side of the intake run, from the air box to the intake manifold.

    I must have something together not quite right.

    edit: BaTu, THANKS! It wasn't the intake manifold bolts, though I went through them anyway, and when I got to #7, when doing my best to not burn myself, just got home, and it's warm outside, I went to move a hose which goes from the left valve cover to...where does this go...oh, nowhere! Wait, here's where it goes...on the rear side of the intake ductwork.

    /facepalm

    Dude, I appreciate it. Part of the problem is, my garage is kinda dark, but it's so warm out there, I turned on the lights and opened both doors. My wife's car not being present meant more light.

  5. #4
    1crock is offline Cadillac Owners Member
    Automobile(s): 2006 STS4
    Join Date
    Apr 2010
    Posts
    43

    Re: PO174 returns for an encore

    Yep, I got taken in by that same hose myself. Oh well, I reckon I'm just a bit late with noting that to do you any good.

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