P0016 Code - Car won't start

[ckrizay]

Recently had the check engine light come on in my cobalt LS with 2.2L ecotech auto transmission. I was not having any issues (driving good though my dad said he heard a ticking when starting it up) but I disconnected and reconnected the battery to make the light go away (disconnected the fuse block first by mistake). After reconnecting everything the car would not start (it turns over but not starting). A scan gave code P0016: crankshaft position-camshaft position correlation (Bank 1 sensor A).
I replaced the crankshaft sensor then the camshaft sensor and neither fixed the problem and allowed it to start.

Anyone have any similar issues or any recommendations?

[Blue Bowtie]

Welcome Aboard!

The CMP timing/phasing relationship to the CKP may have to be re-learned. This can require a bidirectional scanner capable of instructing the PCM to enter the relearn mode.

Also, this is not 1988. Disconnecting the battery to clear error codes is no longer the preferred method, as you found out. Moreover, many times (most?) it does not clear stored DTCs, and maybe not even pending DTCs since much of that data is stored in NVRAM. If it does clear NVRAM all learned data can be lost, like the CMP timing.

[ckrizay]

A mechanic recommended that I check the timing chain is aligned. Is it worth it to check the timing chain if it is as you suggested and just needs to be relearned?

Would not relearning prevent the car from starting, I have seen relearning come up a couple of times but most code websites make no mention of this.
(I am trying to avoid a large bill to tow to a shop to relearn)

[Blue Bowtie]

Disassembling to the point of accessing the chain is no small undertaking, especially on a sidewinder (FWD) installation. Imagine this with the subframe rail right in the way:



You already know how much fun it is to access the CMP.

It would be easier to borrow or rent a scanner that can "talk" to the PCM and try a relearn. If you disassemble to check the chain you'll have to relearn the sensors anyway.

Also, the 134 CID is not terrible for timing chain wear/stretch. The bigger problems are with the tensioners. I had that engine in a '96 Sonoma pickup and ran it up to over 220K with no problems. I'd still have it but the body was rotting off it for the third time. Yours may have experienced slap and skipped, but if there isn't a lot of mileage I wouldn't automatically expect it. Some of them also had cam sprocket issues in the mid-'90s but that got solved after a few years.

What year Cobalt are we working on?

[ckrizay]

It is a 2008 Cobalt LS with ~98k kms on it.

[Blue Bowtie]

Wow, that's a pretty young one, but it's still possible that the chain/tensioner has problems.

Just for argument, when cranking the engine is there spark? The PCM requires a CKP signal to switch the ignition coils, so no spark might point toward the CKP.

If there is spark and no injector pulses, that's more likely the CMP and/or phasing.

If you have both spark AND injector pulses, the chain would be the next suspect - Provided the plugs are not soaking wet with fuel.

[ckrizay]

Took the case off to look at the timing chain- took maybe 30min (not too bad). It definitely looks like the timing chain is off to me though oddly enough there is no marked sprocket to align the exhaust yet there is a red sprocket to guide the intake (all the pictures i have seen have two coloured sprocket to align the intake and exhaust). I have not yet taken off the crank to see the alignment to the crank.



Any advice on difficulty on re-aligning the timing chain?, I am leaning towards sending it to a shop to redo.

Also, is the relearn necessary to run? I am not sure my local mechanic has the tool needed and the tow to dealership would be very large.

Thank you so much for all your help.

[Blue Bowtie]

That lower sprocket is probably going to be the tough one, any why I posted the photo of the single cam version above.

If you want to see what you're facing, check this link:

https://www.youtube.com/watch?v=evJuIsCD6Gs