Auto Repair Glossary
Common auto repair terms explained in plain language. Know what your mechanic is talking about.
Alternator
A device that converts mechanical energy from the engine into electrical energy to charge the battery and power the vehicle's electrical systems. Signs of failure include dimming lights and a dead battery.
Brake Pads
Friction material that presses against the brake rotor to slow or stop your vehicle. They wear down over time and typically need replacement every 30,000 to 70,000 miles depending on driving habits.
Brake Rotor
The flat, disc-shaped metal component that brake pads clamp onto to create friction and stop the vehicle. Rotors can warp over time and may need resurfacing or replacement.
Catalytic Converter
An emissions control device in the exhaust system that converts harmful gases (carbon monoxide, hydrocarbons, nitrogen oxides) into less harmful emissions before they exit the tailpipe.
Check Engine Light (CEL)
A dashboard warning light that indicates the engine control module has detected a problem. It can signal anything from a loose gas cap to serious engine trouble. Diagnostic scanning is needed to identify the exact issue.
Coolant (Antifreeze)
A liquid that circulates through the engine to regulate temperature, preventing overheating in summer and freezing in winter. It should be flushed and replaced periodically according to manufacturer recommendations.
CV Joint
Constant Velocity joint. It connects the transmission to the wheels on front-wheel and all-wheel drive vehicles, allowing power transfer while accommodating steering and suspension movement.
Differential
A gear system that allows the driven wheels to rotate at different speeds, essential for smooth turning. Found in the rear axle of rear-wheel drive vehicles and in both axles of all-wheel drive vehicles.
Exhaust System
The series of pipes and components (manifold, catalytic converter, muffler, tailpipe) that route engine exhaust gases away from the passenger cabin and reduce noise and emissions.
Head Gasket
A seal between the engine block and cylinder head that prevents coolant and oil from mixing and maintains proper compression. A blown head gasket is a serious repair that can cause engine overheating.
OBD-II
On-Board Diagnostics II: a standardized system in all vehicles since 1996 that monitors engine performance and emissions. Mechanics use OBD-II scanners to read diagnostic trouble codes (DTCs).
Power Steering
A system that uses hydraulic fluid or an electric motor to assist with steering effort. Whining noises or difficulty turning the wheel may indicate a power steering issue.
Serpentine Belt
A single, continuous belt that drives multiple engine accessories like the alternator, power steering pump, A/C compressor, and water pump. Should be inspected regularly and replaced if cracked or worn.
Spark Plugs
Small devices that create an electrical spark to ignite the fuel-air mixture in the engine cylinders. Worn spark plugs can cause misfires, rough idling, and poor fuel economy.
Struts & Shocks
Components of the suspension system that absorb road impacts and keep the tires in contact with the road. Worn struts/shocks can cause bouncy rides, uneven tire wear, and longer stopping distances.
Synthetic Oil
Engine oil that has been chemically engineered for superior performance compared to conventional oil. It provides better protection at extreme temperatures and longer change intervals. Required by most European import vehicles.
Thermostat
A valve in the cooling system that regulates coolant flow to maintain optimal engine operating temperature. A stuck thermostat can cause overheating or poor heater performance.
Timing Belt/Chain
Synchronizes the rotation of the crankshaft and camshaft to ensure engine valves open and close at the right time. Timing belt replacement is a critical maintenance item, failure can cause major engine damage.
Transmission Fluid
Lubricant that keeps transmission gears running smoothly. Should be checked and changed at regular intervals. Low or dirty fluid can cause rough shifting and transmission damage.
Wheel Alignment
The adjustment of wheel angles to manufacturer specifications, ensuring even tire wear and straight vehicle tracking. Misalignment can cause pulling to one side and premature tire wear.