Illumination of the Check Engine Light can be caused by a loose or worn gas cap.
2007 Buick Rendezvous Problem Reports
RepairPal Verified 2007 Buick Rendezvous Problem Reports
The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.
The high pressure power steering hose will commonly leak fluid and should be replaced if this is the case.
The front struts may show signs of wear, or be excessively bouncy ride at freeway speeds. This may begin to occur at around 75,000 miles.