Timing Chain Issue on Wife’s Buick

Sandys Regal (2.0 Turbo Ecotec) broke a chain guide. So, I replaced all guides, chain and tensioner. Then it started throwing P0016 and P0017 codes. Basically a disagreement between cams and crank.

So, tore it down again and it appears I was off by two teeth somehow.

When I attempted to realign, I can’t get the chain to line up properly. If I am on the Intake timing mark, then I am two teeth off on the crank pulley and vice versa.

Procedure is to put motor at TDC on Exhaust stroke. Which means the cams are still under load. Could I have inadvertently allowed the Intake cam to roll forward by two teeth?


Craig S

Contributing Member
Sure could have. Some engines have a special tool to hold both cams in the required position so they won't move by accident. Are there marks on both cams and the crank? I have no experience w/ that engine but some models of the Lexus I used to work on, we had to be real careful. Have all three marks lined up, remove the belt, and the smallest inadvertent nudge of the exhaust cam, and wham, it moved 90 degrees or so. All engines I have had apart had marks on both cams and crank.
Yes, marks on all three pulleys. But, when two of three are sync’d the third is out.
I’m not getting any interference when rotating the motor. So, it’s not very far out. Just enough to throw codes and idle just a bit off.

Craig S

Contributing Member
Mike I don't understand why that 3rd can't be moved into the correct position. What prevents it being moved? I just looked at a couple of videos and it seems pretty straight forward. This looks to be a good video.
Note where he needs a large open end wrench to move the left side cam to align the marks.
Got it fixed. Both cams had indexed on me. Had to have a friend rotate Intake cam counter clockwise and exhaust cam clockwise while I lined up the chain.

Tip: use the cam tool to hold them in place!