P0016 after head gasket replacement

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by robbiebags, Sep 25, 2025 at 10:43 PM.

  1. robbiebags

    robbiebags Junior Member

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    Hey guys, I just finished replacing the head gasket for my 2011 prius with 195k miles. Unfortunately, during start up, the engine was still rattling after 10 seconds. Didn't smoothen after a minute so I shut it off. Threw a P0016 code which is timing related. I think I put the timing chain incorrectly(attached is a photo of it). Only 1 mark was correct which was on the intake side cam sprocket. As for the exhaust side cam sprocket, I couldn't reach the mark with my chain's 1 link mark, I'm about 2 teeth off, that's because the intake side cam sprocket turned clockwise by like 15 degrees when the tension was released. I tried to turn the intake cam sprocket counter clockwise so I could reach the mark on the intake but it wouldnt turn. I didn't want to force it either. I was looking into reddit and some stated that it should correct itself after the engine starts. Obviously it didnt after starting the engine after putting everything back together. My heart kinda sunk. I spent 20 hours on this job already.

    Now I have to disassemble the engine again to get to the timing cover and fix the timing. When i was retracing my steps, I realized that the reason why i couldn't turn the intake cam sprocket counter clockwise was because the chain was already installed on the bottom crank sprocket. I now have an idea how to correctly place the marks and hopefully fix the timing issue.

    My question is, did I do any damage to the engine from letting it run for a minute with bad timing? Also, when I go back into the timing chain after disassembly, would all my sprockets be misaligned now due to the improper timing and now have to rotate them? Or do I just have to place the chain in correctly this time?

    This is my biggest DIY on a car ever. Just didnt have the funds to go to the shop. They charged at least $3000 for the job.

    Any input helps. Thanks in advance guys!
     

    Attached Files:

    #1 robbiebags, Sep 25, 2025 at 10:43 PM
  2. PriusCamper

    PriusCamper Senior Member

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    I've read a bunch of posts like this over the past dozen years and have never seen serious damage from timing sprocket position being slightly off.
     
    #2 PriusCamper, Sep 26, 2025 at 12:43 AM
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  3. ASRDogman

    ASRDogman Senior Member

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    Do your best NOT to rush this. Go slow and pay very close attention to the marks and
    the chain.

    Put the engine at TDC first before pulling the timing cover off. With the valve cover off.
    Make sure the sprockets align for TDC, they should be very close, but off because the chain
    of off.
    AFTER you've align the cam to put the sprocket in the correct position.
    If you take cam cover off nearest the
    sprockets, and fold a paper towel a few times and place on top of the cam then put the cover
    on and snug it up, this will keep it from moving.

    Now you can install the chain. It should be tight along the top between the two sprockets.
    And tight between the intake sprocket and crank sprocket.
    The chain will stay tight, and only be loose on the tensioner side. Push the chain toward the center,
    it will more or less stay in place. Carefully install the timing cover.
    Then the tensioner. Of course, you should have retracted the tensioner and rotated the hook to
    keep it inside the tensioner. After installation, you rotate the crank, SLOWLY, counter clockwise,
    which will push the piston back a little and the clip will release, and you'll hear it.
    then rotate the crank back to TDC.

    Then remove the cam shaft cover, and remove the paper towels. Reinstall the cover and torque to specs.
    This is the IMPORTANT part. It's easier with the spark plugs removed. Rotate the crank 720 degrees, two
    full turns. Make sure the mark is at TDC. Then check the intake and exhaust sprockets. They SHOULD
    line up in the correct positions. The timing CHAIN special links will not, that doesn't matter, the sprockets
    must align correctly. If they do, you're all set.

    If you rotate the crank 30 times I think it is, THEN the links on the chain will align with the sprockets.

     
    #3 ASRDogman, Sep 26, 2025 at 7:56 AM
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  4. robbiebags

    robbiebags Junior Member

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    Dude you are the best. Thank you for the write up! I'm understanding everything you've said. I've done hours of research last night on how to fix my timing especially now that it's off timing for sure, but couldn't really find anyone with a video on how to fix it if it's misaligned.

    My question is, how do you align the cam to put the sprocket in the correct position? Do I use a 24 mm wrench to turn the cam? Do I go clockwise or counterclockwise? Also, I'm sure both intake and exhaust sprockets will need to be turned because of the mistiming right?

    Thanks again man. You are a lifesaver. I will be working on my car this weekend a few hours at a time and will post updates here if I hit a roadblock with the timing.
     
    #4 robbiebags, Sep 26, 2025 at 8:19 AM
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