02 318ci help i’m confused

it cut out by time rac arrived it started again drove home fine couple of miles took it to local mech code read it p277bb cam control,outlet p2708 crank sensor ref mark p2782 cam sensor exhaust p227f crank speed sensor, rac thought it was possible crank sensor but mech reckons its the timimg chain and ass gears as the sensors are all independant and one won't effect the others, it runs fine but don't won't to drive it in case it breaks and wrecks the engine.any ideas it sounds exspensive