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 OnStar Additional Information, and an Advisor can run a check.

    See also:

    Vehicle Speed Messages
    SPEED LIMITED TO XXX MPH (KM/H) This message displays when your vehicle speed is limited to 128 km/h (80 mph) because the vehicle detects a problem in the speed variable assist steering system. Have ...

    Automatic Dimming
    If equipped with an automatic dimming mirror, the driver outside mirror adjusts for the glare of the headlamps behind you. See Automatic Dimming Rearview Mirror on page 2‑17. ...

    Tire Pressure
    Tires need the correct amount of air pressure to operate effectively. Notice: Neither tire underinflation nor overinflation is good. Underinflated tires, or tires that do not have enough air, can re ...