Check engine light P0013-P0014

My daughters 2008 Pontiac G6 check engine light came on,checked code
came out P0013-P0014, replaced can shaft sensor light went out for 2 weeks
then came on had code checked again P0013-P0014 came up again, was
told cam shaft sensor was put In wrong, had it taken out and put In again,
check engine light went out, next day back on, could it be a bad sensor or
something else, car has had an oil change