Oldsmobile/Buick Repair: 1990 Olds Cutlass Ciera, olds cutlass ciera, olds cutlass

Question
I just bought this car from it's second owner with 138K on it.  Was told it has been very reliable and so far seems to be.  Couple things, the check engine soon light comes on intermittently.  Usually right after start up then out.  Back on again from about 10 to 30 mph, off again until maybe 55 - 60, then off again.  On again at slow down, then off at idle.  I'm sure there's a sensor faulting somewhere, but don't have the procedure to check codes to isolate.  Secondly, from about 25mph on up a very audible hum and slight vibration occurs.  I was told the car needs a rear wheel bearing, but the hum seems to be coming from up front.  Tires are worn but the tread is even.  Any thoughts?  Thanks.

Answer
hi mike..well the check eng light could be anything most likely from the symptoms.oxegen sensor ..as for the humming noise wheel bearing assy.about 100 plus labor but it will get a lot worse before you have to worry.please take a sec of your time to rate my help  ty billymac