I just put head gaskets in my '98 Tahoe. Now the code reads p1345 ckp/cmp correlation. I had a Firestone Dealer check the timing and they couldn't fix it. What else could it be?

I just put head gaskets in my '98 Tahoe. Now the code reads p1345 ckp/cmp correlation. I had a Firestone Dealer check the timing and they couldn't fix it. What else could it be?

If you had performed a search here, you should have found a number of threads related to this.
Basically the timing is off...you can't time this motor the conventional way, you will need to find someone with a scan tool that reads camshaft position offset...the spec is 0 at 1200 prm.