Every part, explained.
Pick a car part to see what it does, how to spot trouble, and roughly what it costs to fix in the UK.
Top 10 Searched
Car Battery
Stores the electricity that starts your car and powers it when off.
Brake Disc
The shiny metal plate your brake pads squeeze to slow you down.
Engine
The heart of the car — where fuel becomes motion.
Clutch
Connects and disconnects the engine from the wheels.
Alternator
The on-board power station that keeps your battery topped up.
Starter Motor
The muscle that turns your engine over when you twist the key.
Oil Filter
Keeps your engine oil clean so internal parts don't wear out.
Suspension Springs
The coiled metal springs that keep your wheels on the road and your ride comfy.
Spark Plugs
Tiny igniters that set fire to the fuel inside your engine.
Ignition Coil
Turns 12 volts into 30,000+ volts to light the spark plug.
Electrical
5 explainersAlternator
The on-board power station that keeps your battery topped up.
Starter Motor
The muscle that turns your engine over when you twist the key.
Car Battery
Stores the electricity that starts your car and powers it when off.
ECU (Engine Control Unit)
The computer that runs your engine — fuel, ignition, emissions, everything.
Horn
The simple electrical warning device you press to alert other road users
Engine
21 explainersEGR Valve
A small valve that recycles exhaust gas to reduce emissions.
Spark Plugs
Tiny igniters that set fire to the fuel inside your engine.
Turbocharger
Squeezes more air into the engine for extra power.
Intercooler
A radiator-like cooler that reduces the temperature of compressed air before it enters the engine.
Head Gasket
The critical seal between the engine block and cylinder head that keeps coolant, oil, and combustion gases apart.
Oil Filter
Keeps your engine oil clean so internal parts don't wear out.
Timing Belt
The rubber belt that keeps your engine's valves and pistons in perfect time.
Timing Chain
A metal chain (instead of a belt) that times your engine — usually lasts the life of the car.
Serpentine Belt
The long ribbed belt that drives your alternator, power steering and air-con.
Engine
The heart of the car — where fuel becomes motion.
Air Filter
Keeps dirt and grit out of your engine.
Throttle Body
The valve that decides how much air the engine gets.
Fuel System
Stores, filters and delivers fuel to the engine.
Fuel Pump
Pushes fuel from the tank up to the engine.
Fuel Filter
Keeps rust, water and grit out of your injectors.
Ignition Coil
Turns 12 volts into 30,000+ volts to light the spark plug.
Fuel Injectors
Spray a fine mist of fuel into the engine.
Fuel Tank
Where the fuel lives until the engine needs it.
Ignition System
Creates the spark that fires the engine (petrol only).
Carburettor
The old-school mechanical mixer that fed petrol engines before fuel injection took over.
Glow Plugs
The small heaters that help a diesel engine start when it's cold.
Exhaust
4 explainersCatalytic Converter
A clever filter that scrubs harmful gases out of your exhaust.
Diesel Particulate Filter (DPF)
Traps soot from diesel exhaust so it doesn't reach the air.
AdBlue System
The blue fluid modern diesels use to clean up their exhaust.
Exhaust System
Carries waste gases away and quietens the engine.
Braking
9 explainersBrake Pads
The friction blocks that slow your car when you press the pedal.
Brake Disc
The shiny metal plate your brake pads squeeze to slow you down.
Master Cylinder
The pump behind your brake pedal that turns your foot push into stopping power.
Brake Servo
The vacuum-powered helper that makes your brake pedal light and easy to press.
Brake Calipers
The hydraulic clamp that squeezes the pads onto the disc.
Hand Brake
The mechanical backup that keeps your car still when parked.
Brake Fluid
The hydraulic liquid that transmits your foot on the pedal to the brakes at each wheel.
Brake Hoses and Brake Lines
The flexible hoses and steel pipes that carry brake fluid to each wheel.
Rear Drum Brakes and Brake Shoes
An older but still common style of rear brake that uses shoes inside a metal drum.
Drivetrain
6 explainersClutch
Connects and disconnects the engine from the wheels.
Drive Shaft
The spinning bar that delivers engine power to your wheels.
Wheel Bearing
The greased bearing that lets your wheel spin smoothly for thousands of miles.
Gearbox / Transmission
Lets the engine spin at its happy speed at any road speed.
Differential
Lets your driven wheels turn at different speeds in corners.
Dual-Mass Flywheel (DMF)
A heavy clutch component that smooths out engine vibration on its way to the gearbox.
Cooling
6 explainersRadiator
Keeps your engine from overheating on long drives.
Cooling System
Stops the engine cooking itself.
Water Pump
Circulates coolant around the engine.
Thermostat
Controls the engine's operating temperature.
Coolant Expansion Tank
Gives hot coolant somewhere to expand into.
Radiator Fan
Pulls cool air through the radiator when the car isn't moving fast enough to do it on its own
Suspension
8 explainersSuspension Springs
The coiled metal springs that keep your wheels on the road and your ride comfy.
Shock Absorbers
The oil-filled tubes that stop your car bouncing after every bump.
Wishbones / Control Arms
The bone-shaped arms that connect the wheel hub to the chassis and control how the wheel moves.
Anti-Roll Bar & Drop Links
The stabiliser bar and its connectors that keep the car flat and stable through corners.
CV Joints
The flexible joints that transfer power from the gearbox to the wheels while the suspension moves up and down.
Suspension Bushes
The small rubber pads that stop metal suspension parts knocking against each other.
Ball Joints
Ball-and-socket pivots that let your wheels steer and move up and down at the same time.
Struts and Top Mounts
The vertical leg that holds your front wheel up, plus the bearing it pivots on under the bonnet.
Car Servicing and Legal
2 explainersSteering
4 explainersPower Steering Pump
The pump that makes turning the wheel feel light, even when parking.
Steering Rack
The component that turns your steering wheel into wheel movement.
Track Rod / Tie Rod Ends
The links between the steering rack and the front wheels — a common MOT failure.
Electric Power Steering (EPS) Motor
The electric motor that has replaced the old hydraulic pump on most modern cars.
Comfort
6 explainersAir Conditioning Compressor
The pump that makes your air conditioning blow cold.
Heated Seats
Electric warming pads built into your seat cushion and backrest.
Heated Steering Wheel
A warming element wrapped around the rim of the wheel.
Climate Control System
The smart brain that keeps the cabin at the temperature you set.
Air Conditioning System
The whole system that cools, dries and freshens the cabin air.
Cabin Air Filter
A pleated paper filter that cleans the air before it reaches the vents.
Visibility and Convenience
8 explainersWindscreen Wipers
Your first line of defence against rain, snow and road grime
Rain Sensors
How your car knows it is raining before you do
Automatic Headlights
Lights that think for themselves so you never drive in the dark
Auto-Dimming Rear View Mirror
No more dazzling headlights from the car behind
Heated Windscreen
Melts ice and fog away in seconds without a scraper
Rear Window Demister
Clears your back window on frosty mornings in under a minute
Wiper Motor
The small electric motor and linkage that actually swings the wipers across the glass
Headlights and Bulbs
The lights that let you see the road at night and let other drivers see you
Doors and Access
6 explainersCentral Locking
Lock or unlock every door from a single button press
Keyless Entry
Walk up and the car unlocks itself — no key needed
Push Button Start
One press and the engine springs to life
Electric Windows
Effortless glass movement at the touch of a switch
Electric Tailgate
Open or close the boot with a button press or a foot wave
Child Locks
Keep little passengers safely inside
Sensors
10 explainersABS Sensor
The little sensor at each wheel that stops your brakes from locking up.
Oxygen (O2) Sensor
Tells the ECU if the fuel mixture is right.
Mass Air Flow (MAF) Sensor
Measures exactly how much air enters the engine.
TPMS Sensor
A battery-powered sensor inside each wheel that radios its tyre pressure to the dashboard.
Crankshaft Position Sensor
Tells the ECU exactly where the crankshaft is — without it, the engine won't start.
Camshaft Position Sensor
Tracks the camshaft so the ECU knows which stroke each cylinder is on.
Coolant Temperature Sensor
A thermistor screwed into the cooling jacket that tells the ECU and gauge how hot your engine is.
Throttle Position Sensor
A potentiometer that tells the ECU exactly how far you're pressing the accelerator.
Knock Sensor
A tiny microphone on your engine block that listens for harmful knocking sounds and tells the ECU to back off the timing.
Parking Sensor
Ultrasonic sensors in your bumpers that beep faster as you near an obstacle.
Electric Vehicles
6 explainers12V Battery (EV)
Yes — EVs still have a normal 12V battery, and a flat one can stop the car "starting".
EV Traction Battery
The huge high-voltage battery pack that actually powers the car.
Electric Motor
The single moving part that replaces the engine, gearbox and clutch.
Inverter
Converts the battery's DC power into the AC power the motor actually uses.
On-board Charger
The part that lets you charge from a normal home or destination AC charger.
Charge Port / Charging Socket
The socket on the car — usually Type 2 for AC and CCS for DC rapid charging.
Modern Technology
8 explainersInfotainment System
The car's entertainment and control hub.
Apple CarPlay
iPhone, simplified, on the car screen.
Android Auto
Your Android phone, projected onto the dashboard.
Bluetooth Connectivity
Pairing your phone wirelessly.
Wireless Charging Pad
Top up your phone without plugging in.
USB Ports
Charging vs data — they're not all the same.
Digital Instrument Cluster
Screens instead of dials.
Heads-Up Display (HUD)
Speed and directions floating on the windscreen.