The parking brake shoes/pads are just like normal brake pads or brake shoes. The only difference is that they work specifically with the parking brakes.

Powertrain Control Module. The PCM is a powerful computer that manages the Engines Ignition, Fuel Injection, and Emission Systems. In some vehicles it may control the operation of the Transmission and Anti-Lock Brake Systems as well.

Over Head Valve (OHV). An overhead valve engine has its camshaft in the engine block. It uses lifters, pushrods and rocker arms to open and close the valves in the cylinder head.

The oil filter removes most particles and contaminates from your engine’s oil to protect your engine’s internal moving parts.

The oil pan is where the oil in your engine is stored.

The oil pressure sensor measures the pressure at which your engine’s oil is flowing. If the pressure becomes too high or too low, the oil pressure sensor sends a signal to the vehicle’s oil pressure warning light. If you see

The oil pump takes oil from the oil pan and pressurizes it, allowing it to travel throughout the engine and lubricate the engine’s moving parts.

Overdrive is a transmission gear that allows the engine to turn at a reduced rpm for a given road speed.

Overheating occurs when an engine reaches too high of an operating temperature. Overheating may lead to potentially significant engine damage.

When incomplete or no combustion occurs in one or more cylinders due to improper fuel, ignition, cylinder compression, or air.

The muffler is a part of the exhaust system designed to reduce the noise generated by a vehicle.

Natural pollution has been present on earth since before man appeared and continues to be a factor when discussing air pollution, although it causes only a small percentage of the overall pollution problem. It is the direct result of decaying

Neutral (gear). Neutral is actually not a gear. When your vehicle is in neutral, the gearbox and engine are completely disconnected. Thus, your car is able to roll freely whether the engine is on or off.

An acronym for Oxides of Nitrogen, a primary emission produced in the combustion chamber under high temperatures when nitrogen combines with oxygen. Oxides of nitrogen contribute to the formation of smog.

A fuel octane rating measures a fuel’s resistance to knocking or pinging.

The odometer measures how many miles are on your vehicle.

Over Head Cam (OHC). An overhead cam engine has its camshaft in the cylinder head, above the valves and cylinders. This allows the camshaft to directly open the valves without using pushrods.

The ohm (symbol:

Lug nuts attach a car’s wheel to its hub.

Manual chokes have a cable that lets the driver control the carburetor’s choke operation. Most newer cars with carburetors have automatic chokes instead of manual chokes.