Do You Know the Function of These Auto Parts?


By: Steven Symes

6 Min Quiz

Image: shutterstock

About This Quiz

There's a lot that goes into the making of a car and into making it work. Considering how complicated they are these days, since vehicles work as not only transportation, but are also things of comfort, convenience, and connectivity (on the go), it's difficult to know what each and every part in your car does. Most people are fooled by shady mechanics who throw around terms they don't understand and might be too afraid to ask about, which in turn costs them in unnecessary or bogus repairs. 

Maybe you're one of those rare people who know so much about cars, you can tear into one and identify what each part does. If so, you're definitely unique, an elite car expert that gets how everything works from front to back. That's a valuable skill because you'll be able to know when mechanics are lying and can fix things, given enough time and the right tools. 

The best way to see if you qualify as a car nerd is to take this quiz. It will test your knowledge of an array of components and what they do, going well beyond just the engine compartment. Take the quiz now and test your knowledge of auto parts! 

What is the main function of a car fuse?

Like other fuses, the fuses in your car protect the different areas of the electrical system from a sudden and dangerous spike in the flow of electricity. When that happens, the fuse breaks, closing the circuit from damage.


What is the function of your car's gas cap?

If you've ever spilled gas and noticed it evaporated quickly, you know that keeping a cap on the tank is a good idea. If you don't, it can also cause the check engine light to come on, because the system detects a fuel leak that needs to be addressed. It's best to turn the cap until it clicks, so you know everything is sealed up tight.


What exactly does a catalytic converter do?

Catalytic converters, or cats as some people call them, use a catalyst to transform some of the most harmful gases in your exhaust to gases that are less harmful or not harmful at all.


What is the function of shocks on a car?

Because shocks compress, and they're part of the suspension system, they take the shock out of bumps, potholes, and other road imperfections. Without them, riding in a car would be far less comfortable.


What does a connecting rod do?

Connecting rods need to be extremely durable since they must deal with the extreme forces exerted by the pistons after combustion downward, which in turn push the crankshaft to rotate.


What does a lug nut do?

The lug nuts are the giant nuts you see on your car's wheels. Like other nuts, they're fasteners that keep the wheels secured to the hubs, so they don't fly off as you're driving down the road.


Why do cars have third brake lights?

All modern cars have a third brake light, which only illuminates when you press on the brake pedal. When your headlights are on, it can be hard for people sometimes to tell if you've pushed on the brake pedal, if they can only see the taillights. The third brake light eliminates any confusion.


What does your car's alternator do?

An alternator is belt-driven, so it uses the power from the engine to create electricity, which it then uses to recharge the battery and power things like the headlights, radio, dash lights, etc. while you're driving. If this starts to go out, you might have trouble starting your car, or notice the lights dim momentarily as you drive.


What do wheel spacers do for a car?

Wheel spacers bolt onto the axle, just like a wheel, and have studs that you use to bolt on the wheel. They will increase the wheel offset, plus they can change the bolt pattern if you so desire.


What do fog lights do on a car?

Fog lights have a wide and short beam pattern, plus they're mounted low on a car. That helps you see better in fog, heavy rain, snow, and similar situations. Trust me, turning on your brights has the exact opposite effect.


What is the purpose of a car's clutch?

The clutch literally creates or bridges the connection between the engine and transmission, which sends power to the wheels. It allows the wheels to turn at one speed, and the engine to turn at another.


What is the purpose of engine mounts?

Engine mounts not only attach the engine to the car's frame, they're also designed to soak up some, most, or all of the engine vibrations. How exactly they do that depends on the specific mounts, which determines how comfortable of a ride you'll have.


What is the heater core's job?

Most people turn on the heater in their car without a second thought. That hot air comes from the coolant flowing out of the engine, which travels to the heater core before making its way through the rest of the cooling system, so you can stay warm when it's cold outside.


What is the purpose of a car's valves?

The valves sit in your engine's cylinder head(s) where they control when the air-fuel mixture enters the cylinders, and when the exhaust gases leave. How these work really impacts engine performance.


What is the function of knee airbags?

Knee airbags sit in the lower portion of the dashboard, covering either the driver and/or the front passenger. In a crash, they keep the knees from hitting the dash, which is a common leg injury in car accidents.


What is the function of the MAF?

The mass airflow sensor has one function: measure how much air is flowing into the engine. That info is sent to the ECU or management computer, which adjusts how much fuel is being injected into the engine, for an optimal mix of the two.


What does a radiator do?

As the coolant flows through the engine, it picks up considerable amounts of heat, which is exactly what the coolant should do. The radiator allows air to flow through it, cooling off the coolant rapidly, so it's ready to circulate through the engine again.


An intercooler obviously has something to do with cooling, but what exactly particularly does it cool?

An intercooler is part of a forced induction setup, usually for turbocharged cars, but sometimes for supercharger setups. The air passes through what looks like a mini radiator, cooling it further before it flows to the engine, helping to boost performance.


What is the function of brake calipers?

When you press on the brake pedal, the pressure you create in the lines causes the calipers to pinch the rotors, only it's the pads attached to the calipers that push against the rotor. Without functioning calipers, your brakes wouldn't do anything, and you'd crash.


What is the function of a camshaft?

In modern engines, one or more camshafts spin at the top of the cylinder head. Because they have lobes that are oblong, this motion will push the valves open for a short period, either letting the air-fuel mix into the cylinders or the exhaust gases out.


What job does a car's thermostat fulfill?

The thermostat in your car sits between the radiator and engine, controlling when the coolant flows to the radiator and doesn't. It's triggered by the temperature of the coolant, so your engine warms up quickly but doesn't overheat.


What does the crank sensor do in your car?

This electronic component works in gasoline and diesel engines to measure how the crankshaft is moving at any given moment. That info is sent to the ECU, which can then adjust timing, fuel injection, or other factors as needed.


What role does a head-up display fill for a driver?

The head-up display on a car either projects information onto the windshield or in some designs, it's a see-through screen that extends up to the windshield area on the dash. The whole point is to give you minimal but useful info like vehicle speed, navigation directions, and critical alerts so you can read them without looking down, keeping your eyes on the road.


What is the function of a car's fuel rail?

The fuel rail on your car attaches to the injectors, and it keeps the fuel pressurized, so everything flows precisely. Essentially, the fuel rail is a pipe, although its design is highly specialized.


What is the purpose of a shift fork?

In a car with a manual transmission, when you move the stick, you're actually moving the shift fork at the same time. It slides gears so they're either engaged or not engaged with other gears in the transmission, changing the gear ratio.


What does a car balancing shaft do?

Some engine designs aren't well-balanced, so the solution is to use a balancing shaft. The eccentric weighted shaft works to counteract engine vibrations, so you don't feel them as you drive at any speed.


What does a crankshaft do?

The crankshaft sits at the bottom of the engine, where it's connected to the pistons through the connecting rods. As the pistons move up and down, the crankshaft rotates, sending that spinning energy to the clutch and the transmission.


What do glow plugs do in a vehicle?

Diesel fuel can gel in really cold conditions, making it impossible to start a vehicle unless you have a way to get it flowing. That's where the glow plug comes in, because it's designed to get things moving by heating up the fuel just enough.


What does a heat extractor do?

Some cars have heat extractors on the hood or in the fenders. They're vents, but are pointed so the air flows out and toward the back of the car, instead of ramming into the vent from the front.


What job does a car's oil sump perform?

The oil sump is really just a place where the engine oil collects. Sometimes called the oil pan, the sump is where the oil pump draws oil to circulate around the engine and other components.


What does a rear diffuser do?

The rear diffuser is a specially shaped section of a car's underbody. It helps the air transition from high-velocity flow under the car to a slower movement behind it, which in turn boosts aerodynamics. That means improved handling, acceleration, and efficiency.


What is a breather's function?

The breather attaches to the PCV valve using a vacuum to draw fresh air into the crankcase and forcing gases produced by combustion out of the engine. Without this feature, certain engines would accumulate harmful chemicals and even water, which would be disastrous.


What does a fuel pump relay do?

The fuel pump relay controls when the fuel pump draws electricity off the oil pressure sending unit, or other nearby components. If the relay starts to fail, you'll have problems starting the engine or see that the engine no longer runs as strong as before.


What is the job of the control arms?

The control arms use bushings to connect up to the vehicle frame, and a ball joint to attach to the suspension, at least in most designs. They're designed to minimize the transfer of vibrations from the suspension to the frame, but that's not their primary purpose.


What job does a seat belt pretensioner perform?

Similar to an airbag, the seat belt pretensioner detects when the car hits something, pulling the belts tight. That means you're forced to sit up straight, which reduces the risk of injury during a crash.


Explore More Quizzes

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!