The ultimate car owner’s Jargon Buster

Ever feel overwhelmed by the technical language surrounding cars and repairs? Not sure where to begin when it comes to explaining and understanding car maintenance? Don’t worry, we’re here to help.

At Fixter, we want to make caring for your car as easy and convenient as possible. This includes demystifying the complex language related to car maintenance and ensuring that car owners understand what’s wrong with their car and how it can be fixed. That’s why we’ve created a handy car care jargon buster to help you wrap your head around the tricky automotive lingo, brush up on your knowledge of common car maintenance terms, and diagnose underlying car problems.


ABS = Anti-lock Braking System. Computerised system that uses sensors at each wheel to sense when the wheels are about to lock, and releases the brakes to prevent locking.


Air bag = An inflatable bag that inflates in the event of a sudden impact, to protect the driver and/or passengers from injury. They typically inflate with nitrogen gas at a speed of 1/20 of a second (faster than the blink of an eye), then deflate immediately following inflation, absorbing the impact as they do so.


Air conditioning (Aircon or AC) = A system that enables the temperature of the air inside the car to be lowered, and dehumidifies the air. A lifesaver on a hot summer’s day and great for rapid demisting.


Air filter = A renewable paper or foam filter that removes foreign particles and debris from the air that is drawn into the engine.


Airflow sensor = A sensor used in the engine management system to measure the amount of air being sucked into the engine.


Alternator = An electrical generator driven by the engine. It provides electricity to charge the battery and for the car’s electrical system when the car is running.


Anti-roll bar = A metal bar used in front and/or rear suspension systems to reduce the tendency of the car’s body to roll from side to side. Not all cars have them.


Automatic transmission fluid = A fluid that cools the transmission system and lubricates moving parts in automatic cars. Make sure your car’s transmission fluid level is always up to ‘full’ on the reservoir, but don’t overfill it.


Balljoint = A maintenance-free flexible joint used mainly in suspension and steering systems to allow for movement of the components. Consists of a metal ball and cup, with a rubber seal to retain the grease.


Battery = A ‘reservoir’ that stores electricity. It provides the power to start the engine, and powers the electrical systems when the engine is off. It is charged by the alternator when the engine is running.


Bore = A term used to describe the diameter of a cylinder in an engine.


Brake bleeding = A procedure for removing air from the brake hydraulic system.


Brake caliper = The part of a disc braking system that houses the brake pads and the hydraulic pistons. The caliper straddles the brake disc.


Brake disc = A rotating metal disc coupled to a roadwheel, which is clamped between two brake pads in a braking system. As the brake disc slows down due to friction, so does the car’s wheel.


Brake fluid = A hydraulic fluid resistant to high temperatures, used in hydraulic braking systems and some hydraulic clutch systems.


Brake pad = A metal plate, with a pad of hard-wearing friction material bonded to one side. When the brakes are applied the hydraulic pistons in the brake caliper push the brake pads against the brake disc.


Cam belt = See Timing belt.


Camshaft = A rotating shaft driven from the crankshaft, with lobes or cams used to operate the valves, via the valve gear.


Carburettor = A device used to blend the air and fuel mix in an engine to create the correct ratio for combustion. Carburettors have been replaced by fuel injectors, but are still found in older cars and machines with a small engine, such as lawnmowers.


Catalytic converter = A device fitted in the exhaust system that reduces the amount of harmful gases released into the atmosphere.


Coolant = A liquid consisting of a mixture of water and antifreeze, used in a car’s engine cooling system.


Coolant (water) pump = A pump driven by the engine that pumps the coolant around the cooling system.


Cooling fan = Electric or engine driven fan mounted at the front of the engine compartment and designed to cool the radiator.


Crankshaft = A cranked metal shaft that translates the up-and-down motion of the pistons and connecting rods into rotary motion.


Cylinder = A metal tube in the engine, in which a piston slides.


Cylinder head = The machined component that sits on top of the cylinder block, closing it to create the combustion chambers. It is important that there is good sealing between it and the block.


Cylinder head gasket = A gasket fitted to provide a leak-proof seal between an engine’s cylinder block and cylinder head.


Diagnostic check = performed by a mechanic to check for vehicle sensor faults. A specialised code reader is used to detect problems with your vehicle which may be difficult to spot manually.


Diagnostic light (engine warning light) = A warning light on a car’s dashboard that illuminates when a fault code has been stored in the engine electronic control unit memory.


Dipstick = A metal or plastic rod with graduated marks to check the level of a fluid.


Distributor = A device used to distribute the ignition HT circuit current to the individual spark plugs. The distributor may also control the ignition timing.


Drive belt = A belt, usually made from rubber, used to transmit drive between two pulleys or sprockets. Often used to drive the camshafts and engine ancillaries.


ECU (Engine Control Unit) = A unit that controls all elements of the engine to ensure optimum performance. Using a series of sensors, the ECU interprets data and uses it to control air/fuel mix, valve timing and more. It also monitors the emissions from the exhaust system and can sense when a problem has occurred. An engine warning light is illuminated when the ECU has discovered a problem.


EFI = Electronic Fuel Injection

EGR = Exhaust Gas Recirculation. An emissions control system that recirculates a proportion of the exhaust gases back into the engine, where they are burnt with fresh air/fuel mixture. Controlled by the EGR valve.


Engine oil = A fluid that lubricates all moving parts within the engine, reducing wear whilst allowing components to move freely. The engine oil level can be checked using a dipstick, and should be changed in line with the service schedule recommended by the manufacturer to maximise the life of the engine.


Engine warning light = See Diagnostic light


EV (Electric Vehicle) = A blanket term to describe any type of vehicle that is primarily powered by an electric motor.


Exhaust manifold = A device used for ducting the exhaust gases from the engine’s cylinder head into the exhaust system.



Fan belt = Another term for a drive belt. The term came about because on older cars a drive belt was used to drive the cooling fan. Electric cooling fans are used on most modern cars.


Fault code = An electronic code stored in your car’s electronic control unit which gives details of a fault detected by the self-diagnostic system. A warning light will usually illuminate to indicate a fault. A vehicle diagnostic check can help get to the root of the fault.


Fuel filter = A replaceable metal or plastic filter which prevents particles and contaminants in the fuel tank from reaching the engine.


Fuel pump = A small pump which sends the fuel from the tank to the engine. This is usually found in the fuel tank itself, and is electrically-powered on most modern cars.


Glow plug = The spark plug of diesel engines. An electrical heating device fitted into a diesel engine to help it start from cold. They help achieve the correct temperature by warming the air in the combustion chamber. Each cylinder usually has its own glow plug.


Head gasket = See Cylinder head gasket.


Hydraulic = A term used to describe the operation of a component or system using fluid pressure.


Idle speed = The running speed of an engine when the throttle is closed (when the car is at rest and the driver isn’t pressing the accelerator pedal).


Ignition coil = An electrical coil used to convert power from the low voltage systems used throughout the vehicle into the spark needed for an effective ignition in petrol vehicles.


Ignition system = The electrical system that controls the spark used to ignite the air/fuel mixture in petrol engines.


Ignition timing = Controlled by the ECU, ignition timing refers to the exact point at which a spark should occur in the combustion chamber, triggering ignition. The firing point is relative to the crankshaft speed and the position of the pistons.


Jump leads = Heavy electrical cables which connect one car battery to another for emergency starting.


MAF (Mass Airflow Sensor) = See Airflow sensor.


Master cylinder = A cylinder containing a piston and hydraulic fluid, directly coupled to a foot pedal. Used for transmitting fluid pressure to the brake or clutch operating mechanisms.


MOT test = An MOT is a test which, by law, must be done each year on all road vehicles in the UK that are more than 3 years old. It is a test of vehicle safety, roadworthiness and exhaust emissions.


OBD (On-Board Diagnostics) = A system that monitors the operation of the engine management system and records any faults.


Oil filter = A renewable, cartridge-style filter fitted to an engine’s lubrication system, and used to remove particles, dirt and abrasive matter from the engine oil.


Oil pump = A pump used to move engine oil through the engine internals, lubricating moving parts.


Piston = A component which slides in a close-fitting cylinder. The pistons in an engine compress the air/fuel mixture, push the burnt gases out the exhaust and transmit power to the crankshaft.


Power steering = Steering that is aided by electric or hydraulic motors. This reduces the effort required by the driver to steer the car, particularly at low speed.


Power steering fluid = The fluid in the hydraulic system which is used to reduce the physical effort of turning the steering wheel.


Radiator = The main part of a car’s cooling system. It ensures the engine maintains an optimum working temperature. Your car’s radiator sits at the front of the car, and is used to continuously dissipate heat from the coolant/antifreeze mix circulating through the engine.


Refrigerant = A fluid used to absorb heat in the air conditioning system.


Service = A car service is a maintenance check-up that’s carried out at set time intervals (at least every year) or after the vehicle has travelled a certain number of miles. The car manufacturer specifies the service intervals in a service schedule.


Shock absorber = Forming part of the suspension system, the shock absorber controls the up and down motion of a vehicle’s wheels. They reduce the excessive up and down movements, keeping the car’s body steady on the road.


Spark plug = Spark plugs create the spark needed to ignite the petrol/air mixture in the combustion chamber. These sit in the engine cylinder, and create a spark to ignite the engine.


Starter motor = A starter motor is a small electrical motor used to start the engine. It uses power from the battery to turn the crankshaft via the flywheel and start the engine.


Steering rack = This connects the two front wheels, and is part of a rack-and-pinion steering system. Parallel to the front axle, the steering rack moves left and right as the wheels turn.


Suspension = A general term used to describe the system that insulates a car’s body from the wheels, and keeps all wheels in contact with the road surface.


Thermostat = A device which helps the engine warm up by preventing the coolant from flowing through the radiator until a specific temperature is reached. The thermostat then regulates the temperature of the coolant.


Throttle valve = A flap valve on a petrol engine, controlled by the accelerator pedal – it determines the amount of air entering the engine.


Timing belt (cam belt) = A timing belt is a toothed drive belt used to transmit drive from the crankshaft to the camshaft(s).


Timing chain = Metal flexible link chain that engages with sprockets, it transmits drive from the crankshaft to the camshaft(s).


Torsion bar = A metal bar which twists about its own axis. Forms part of some suspension systems.


Transmission = Most often refers to the type of gearbox employed by a vehicle, typically automatic (auto) or manual.


Turbocharger = A device that uses a turbine driven by the engine exhaust gases to drive a compressor which forces air into the engine This increases the air/fuel mixture flow into the engine to increase the engine’s power.


Water pump = See Coolant pump


Wheel alignment = Wheel alignment is the process of adjusting components to a specified camber, toe, caster and ride height to balance the suspension and improve tyre wear.


Wheel bearing = Wheel bearings allow wheels to turn rapidly and spin freely without generating an excessive amount of heat.

About Fixter

Fixter is revolutionising the car maintenance industry, one repair at a time. Fixter was founded to make car maintenance as easy as booking a taxi. Digital, transparent and stress-free, with world-class customer service. Since launching in Manchester in 2017, Fixter has expanded to more than 100 towns and cities across the UK and provided thousands of car owners with honest, convenient and affordable car repair services.