WARNING:
Leaving children in a vehicle with the ignition key
is dangerous for many reasons, children or others
could be badly injured or even killed. They could
operate the power windows or other controls or
even make the vehicle move. The windows will
function with the keys in the ignition and children
could be seriously injured or killed if caught in the
path of a closing window. Do not leave the keys in
a vehicle with children.

The key can be used for the ignition and all locks.
The key has a bar-coded key tag that the dealer/retailer or qualified locksmith can use to make new keys. Store this information in a safe place, not in your vehicle.
Notice: If you ever lock your keys in the vehicle, you may have to damage the vehicle to get in.
Be sure you have spare keys.
If you are locked out of your vehicle, contact Roadside Assistance. See Roadside Assistance Program.
Remote Keyless Entry (RKE) SystemChevrolet Cobalt Service & Repair Manual. Troubleshooting
When troubleshooting the hydraulic
brake system, perform the following inspections.
Master Cylinder Internal Fluid Leakage Check
Start engine and depress the brake
pedal. If the pedal gradually falls under constant pressure, the hydraulic
system may be leaking. Raise ...