They will run fine even with the stretched chains. The computer is measuring the difference between the camshafts tone ring spaces and the crankshaft ring. They will set a code with less than 3 degrees difference between the two. I've done a couple like this and the actual stretch in the chains is VERY small. But when added up in the three chains it's enough to throw things out of whack enough to set these codes. Many vehicles are set up this way now.
One way to verify it's chain stretch would be to pull a valve cover. Put a wrench on the crank and turn the engine backwards and see how far it moves before the cam moves.
The sensors themselves won't set those codes even if they fail. They would set different codes then.
Thursday, June 1st, 2017 AT 10:57 PM