What did the mechanic just say?

Look up the word on your repair estimate. Each page tells you what the part does, why a shop recommends the work, how urgent it usually is, and what to ask.

• AlternatorThe engine-driven generator that makes electricity for the car and keeps the battery charged.
• Ball jointA pivot that connects the wheel to the suspension so it can steer and move up and down over bumps.
• Brake caliperThe clamp at each wheel that squeezes the brake pads against the spinning disc to stop the car.
• Brake padsBlocks of friction material that press against the brake discs to slow the car, and wear down as they do.
• Brake rotor resurfacingShaving a thin layer off the brake discs so the pads grip a smooth, flat surface.
• Cabin air filterA filter that cleans the outside air before your heater and air conditioning blow it into the passenger area.
• Catalytic converterA part in the exhaust that turns the worst engine fumes into less harmful gases.
• Control armA hinged metal link that holds a wheel to the car's frame and lets it move up and down.
• Coolant flushDraining the old engine coolant and refilling with fresh.
• CV axleThe shaft that carries power from the transmission to a wheel while letting it steer and bounce.
• EGR valveA valve that feeds a small amount of exhaust back into the engine to cool combustion and cut polluting emissions.
• Fuel pumpAn electric pump, usually inside the gas tank, that pushes fuel up to the engine.
• Head gasketThe seal between the two main halves of the engine that keeps combustion, coolant, and oil apart.
• Ignition coilA part that turns the battery's low voltage into the high voltage a spark plug needs to fire.
• Mass airflow sensorA sensor that measures how much air enters the engine so the car's computer can add the right amount of fuel.
• Master cylinderThe part that turns your push on the brake pedal into fluid pressure that works the brakes at each wheel.
• Motor mountA rubber-cushioned bracket that holds the engine in place and soaks up its vibration.
• Oxygen (O2) sensorA sensor in the exhaust that tells the engine computer whether it's burning too much or too little fuel.
• PCV valveA small one-way valve that routes engine fumes back into the engine to be burned instead of leaking out.
• RadiatorThe grid of thin tubes and fins at the front of the car that cools the liquid running through the engine.
• Serpentine beltOne long rubber belt that the engine spins to power things like the alternator and A/C.
• Spark plugsSmall parts in a gasoline engine that make the spark to light the fuel, one for each cylinder.
• StarterAn electric motor that spins the engine for a moment so it can fire up and run on its own.
• StrutsThe combined spring-and-shock units that hold the car up and keep it from bouncing.
• Sway bar linkA short rod that ties the sway bar to the suspension so the car leans less in turns.
• ThermostatA small valve that controls coolant flow to keep the engine at the right temperature.
• Throttle body cleaningCleaning the valve that controls how much air goes into the engine.
• Tie rod endThe small pivoting joint that connects your steering to each front wheel.
• Timing beltA toothed belt that keeps the engine's valves and pistons moving in step.
• Transmission fluid serviceDraining the old fluid from the transmission and refilling it with fresh fluid, sometimes with a new filter.
• Valve cover gasketA seal around the lid on top of the engine that keeps the oil inside from leaking out.
• Water pumpThe pump that pushes coolant through the engine and radiator so the engine does not overheat.
• Wheel alignmentAn adjustment of the suspension so all four wheels point straight and sit at the right angle to the road.
• Wheel bearingThe set of steel balls or rollers that lets each wheel spin smoothly.