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.

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    Engine Exhaust
    WARNING Engine exhaust contains carbon monoxide (CO) which cannot be seen or smelled. Exposure to CO can cause unconsciousness and even death. Exhaust may enter the vehicle if: • The vehicle idle ...

    Tire Pressure Light
    For vehicles with the Tire Pressure Monitor System (TPMS), this light comes on briefly when the engine is started. It provides information about tire pressures and the TPMS. When the Light Is O ...

    Exterior
    GM says the Yukon Hybrid's exterior changes are intended to make the SUV more aerodynamic compared with the gas-powered Yukon. A modified bumper drops the regular Yukon's fog lights for some chunk ...