Mostly educated guess given the air flow over the vehicle.
As for fixing the error, I can't say. It could be the sensor or anything inline of it from wiring to a faulty alternator. I gave up on after awhile myself...my mechanic saw that same fault in a few sunfires and it was never the cam sensor XD
I will say, despite the auto 3 being inefficient and that fault, cruise control at 55 still got me 32mpg and playing with highspeed eoc I got 47 with average speed of about 52. And I did eoc p&g for nearly 160 miles. Only tried starting it while it was already running a couple times. Not a good idea woth that 3spd though
