Sensors provide the data necessary for the vehicle's computer to make decisions and monitor everything from simple vehicle information like tire pressure to complexities like the chemical content of an engine's exhaust.

Preignition results from the buildup of fuel deposits and/or oil in the combustion chamber. These deposits increase chamber pressure and reduce heat tranfer to the coolant. The trapped heat then raises the temperature of the air-fuel mix to the point that it combusts before ignition.

The muffler follows the catalytic converter and absorbs sound to help quiet load exhaust. It is followed by the exhaust pipe which is the final exit point for exhaust gas from the vehicle.

Control arms (upper and lower) connect a vehicle's suspension to the frame. The connection to the wheels is through ball joints which allow the control arms to turn and move up and down simultaneously. The frame connection uses bushings.

The transfer case splits engine power between the front and rear axles of four-wheel drive vehicles.