According to the Service Manual, a P0101 is:
Mass Air Flow (MAF) Sensor Performance.
Basically means the sensor that's on your air intake is either dirty or going bad. Get some MAF Cleaner from your local auto store, take it out and clean it, put it back and unplug the battery for a bit to reset it. If the code comes back, replace the MAF sensor.
PO101 Mass Air Flow (MAF) Sensor Circuit Low Frequency
what is fault code P0102 in a Chevy Tahoe?
Powertrain Control Module Fault. It can also be a problem with the cooling system. I recommend you seek professional help at a GM dealership as there are TSBs on this code on your Cobalt.
discovered the catalytic converter was the issue. the converter was broken down and clogged. replaced and truck runs fine. Good report, thanks.
inefficient catalyst
Left front tire pressure monitor fault signal.
catalyst system fault
Igniton System or Misfire
SYSTEM TO RICH ( bank 2 ) That is the code.
Trouble code P0304 means: Cylinder 4 Misfire Detected
Trouble code P0170 means: Fuel Trim (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)