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Thread: 2012 CX-9 Crankshaft Position Sensor questions

  1. #1
    Registered Member

    CX-9 Grand Touring

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    Jul 2017
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    2012 CX-9 Crankshaft Position Sensor questions

    Hi all,
    Wife's car is a 2012 CX-9. It recently threw a CEL for the rear bank crankshaft position sensor (intermittent). Car runs great but the light comes back after clearing.

    Connector is seated fine and both banks have the same resistance, continuity, and voltage for wiring and sensor. So no smoking guns there.

    I was thinking about swapping sensors between front and rear banks to see if the CEL moves to the other one (meaning bad sensor) or stays put (bad wiring). However, I can't for the life of me figure out how this sensor is installed. It pokes through the valve cover and does not seem to budge or twist. most of these sensors I've seen have a flange and bolt, but not on this one that I can see.

    Internet has been useless and finding the "real" workshop manual has been frustrating. I thought I found one for a 2008 but the sensor location and general engine look in the diagrams was wrong. The web searches kept sending me here, so I figured I would ask.

    So how is this sensor mounted? Do I have to remove the valve cover to replace it?

    All help appreciated!

    Thanks,
    Anthony

  2. #2
    Registered Member

    2008 Mazda CX-9 Touring FWD . 2014 CX-5 GT FWD

    Join Date
    Dec 2007
    Location
    Chicago
    Posts
    61
    Quote Originally Posted by Alacris View Post
    Hi all,
    Wife's car is a 2012 CX-9. It recently threw a CEL for the rear bank crankshaft position sensor (intermittent). Car runs great but the light comes back after clearing.

    Connector is seated fine and both banks have the same resistance, continuity, and voltage for wiring and sensor. So no smoking guns there.

    I was thinking about swapping sensors between front and rear banks to see if the CEL moves to the other one (meaning bad sensor) or stays put (bad wiring). However, I can't for the life of me figure out how this sensor is installed. It pokes through the valve cover and does not seem to budge or twist. most of these sensors I've seen have a flange and bolt, but not on this one that I can see.

    Internet has been useless and finding the "real" workshop manual has been frustrating. I thought I found one for a 2008 but the sensor location and general engine look in the diagrams was wrong. The web searches kept sending me here, so I figured I would ask.

    So how is this sensor mounted? Do I have to remove the valve cover to replace it?

    All help appreciated!

    Thanks,
    Anthony
    Wait, what code number? CRANKshaft (CKP) or CAMshaft position sensor? I'm going to assume it's the CAM sensors you're talking about as the CRANKshaft position sensor is underneath the engine.


    Your CAMshaft position sensors are in the same place as the 2008 3.7L engine. You do not need to pull the valve covers, but will likely need to pull the air cleaner.

    The 2008 manual I use can be found here:
    https://www.dropbox.com/sh/yjma0fz8e...l669LHUja?dl=0

    Once you loosen the retaining bolt for the sensor it should just pull out. There is an o-ring that needs to be lubricated, so it may just be stuck.




    CPS problems can sometimes be frustrating to troubleshoot. Mine are fine on the CX-9, but I had a BMW once that used to die unexpectedly without codes and it all came down to a flaky CPS. Hopefully yours is not something more than a flaky sensor or wiring. Sensors are around $80 to replace, while a bad PCM will cost upwards of $600. Swapping the sensors is also where I would start.

    If you ohm'd out the sensors and they fell within spec (800-1,320 ohms), then your troubles may be elsewhere, but that's not a guarantee. Have fun and let us know what you find.
    Attached Images Attached Images
    Last edited by Thaumaturge; 07-14-2017 at 10:41 AM.

  3. #3
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    CX-9 Grand Touring

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    Thanks. Now I'm wondering what I was looking at? Cylinder thingy sticking up from the passenger side of both banks with electrical connectors on it.

    I saved that to my Dropbox and will probably use it as a reference quite often. Thanks again.

  4. #4
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    CX-9 Grand Touring

    Join Date
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    Now that I have the manual to look through, I think I was looking at the OCV. I'm guessing that's for some sort of variable valve feature. I'll do the proper inspection on the CMP tonight.

    Thanks again!

  5. #5
    Registered Member

    2008 Mazda CX-9 Touring FWD . 2014 CX-5 GT FWD

    Join Date
    Dec 2007
    Location
    Chicago
    Posts
    61
    You're welcome.

    Yep, you were looking at the OCV solenoids that control the oil going to the VVTs. LOL, I should have caught that when you said they were poking through the valve covers. Be thankful you're not concerned with those yet.

    Have fun.

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