2011 Chevy Cruze P0171, U0100, U0140, U0073, Stabilitrak - Fixed

Codes: P0171 Fuel system too lean bank 1 U0100 Lost comm. with ecm/pcm invalid serial data received U0140 Lost comm. with body control system U0073 Control module comm. bus A off Symptoms: Rough idle, occasional stalling. SES light, stabilitrak light comes on with a near stall event. Fix: Replace valve cover All from a bad pcv valve, or technically a bad valve cover. When the idle would drop really low from the vacuum leak, system voltage would drop too low, causing modules to temporarily lose communication, causing all sorts of codes. I blocked off the pcv system, test drove, and every issue listed was gone. No codes came back, whereas before they would immediately during a near stall event. 1.8L 4 cylinder.