The vehicle has a battery saver feature designed to protect the vehicle's battery.
When any interior lamp is left on and the ignition is turned off, the battery rundown protection system automatically turns the lamp off after 20 minutes.
This prevents draining of the battery.
Chevrolet Cobalt Service & Repair Manual. Description
The TPMS (Tire Pressure Monitor
System) warns the driver when a significant loss or gain of tire pressure
occurs in any of the four tires, and allows the driver to display the individual
tire pressures and the locations on the DIC (Driver Information Center)
display. The syste ...