02 chevy cavalier crank/no start

My cavalier will not start. It cranks but wont start. It popped codeu1016 lost communication with ecm and code p1626 anti theft system fuel enable circuit (not sure if the two are related). However my theft light only comes on sometimes and then only for a couple seconds. It does not stay on or flash like all the other scenarios i have read about dealing with the theft system. What could be my problem? Is there a specific part i need to be looking at? Is the resistor bypass worth doing?