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:

    Checking Engine Oil
    It is a good idea to check the engine oil every time you get fuel. In order to get an accurate reading, the oil must be warm and the vehicle must be on level ground. The engine oil dipstick hand ...

    Shifting Into Park (Automatic Transmission)
    WARNING It can be dangerous to get out of the vehicle if the shift lever is not fully in P (Park) with the parking brake firmly set. The vehicle can roll. If you have left the engine running, the ...

    When to Check and Change AutomaticTransmission Fluid
    A good time to check your automatic transmission fluid level is when the engine oil is changed. Change the fluid and filter at the intervals listed in Additional Required Services on page 482, and ...