Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the vehicle is equipped with the Tire Pressure Monitoring System.
If a diagnostics check is needed between e-mails, push 
, and an Advisor can run a check.
See also:
Starting the Engine
If the vehicle has a diesel engine, see the Duramax diesel supplement for more information.
If the vehicle is a hybrid, see the hybrid supplement for more information.
Notice: Do not try to shift to ...
Fuel Used
Press the trip/fuel button until FUEL USED displays. This display shows the number of liters (L) or gallons (gal) of fuel used since the last reset of this menu item. To reset the fuel used informatio ...
Entering the Feature Settings Menu
1. Turn the ignition on and place the vehicle in P (Park).
To avoid excessive drain on the battery, it is recommended that the headlamps are turned off.
2. Press the customization button to enter th ...