Car basics · First steps · about 15 minutes to learn

Read Dashboard Warning Lights

Warning lights are your car's way of telling you something needs attention. The color tells you how urgent it is, and the symbol tells you which system has a problem. Knowing the main ones helps you decide whether to keep going, pull over, or get help.

When to teach it: Learn the colors from about 8, quiz each other from about 10, and know the main lights well before driving lessons.

You'll need

Your car's owner's manual (the warning light section)
A few minutes in the parked car

Step by step

Tick each step as you go if you like; ticks stay on this device.

Open the manualFind the warning light section in your owner's manual. Symbols and meanings vary by car, so your manual is the final word.
Learn the colorsRed means a problem that needs attention right away. Yellow or amber means something needs checking soon.
Watch the bulb checkTurn the ignition to ON without starting the engine. Several warning lights glow, which shows they work. Lights like oil pressure and check engine should go out once the engine starts.
Check engine lightA steady light means the car's computer found a possible problem, often with emissions. Make sure the gas cap is tight; if the light stays on, have the car checked. If it flashes, the problem could cause serious damage, so avoid driving until it's repaired.
Oil pressure light (red)Oil pressure is low. Pull over as soon as it's safe, turn off the engine, and check the oil level. If the light stays on after adding oil, don't keep driving; have the car inspected.
Temperature light (red)The engine is overheating. Pull over when it's safe, turn off the engine, and let it cool before checking coolant or calling for help.
Battery or charging lightThe charging system isn't working right; it could be the alternator or its belt, not only the battery. Get to a repair shop soon, before the battery runs down.
Tire pressure lightOne or more tires are well below the right pressure. Check and fill them. If the light flashes for about a minute and then stays on, the monitoring system has a problem.
Brake lightIt comes on when the parking brake is set. If it stays on after you release the parking brake, the brake fluid may be low or the brakes may have a problem. Stop in a safe place; if you see a leak or the brakes don't feel right, don't drive. Have it towed.

Physics

How it works: Sensors, the car's computer, and the tire light

Your car is full of sensors. A sensor measures something, like oil pressure, engine temperature, or how fast a wheel is turning, and turns it into an electrical signal. The car's computer keeps reading these signals. When a reading goes outside the safe range, the computer turns on a warning light.

The check engine light is part of the car's on-board diagnostics. When the computer finds a fault, it saves a trouble code, a short code made of letters and numbers that points to the problem. A mechanic plugs a scanner into the car to read it.

Tire pressure monitors work in one of two ways. Direct systems put a small battery-powered pressure sensor inside each tire that sends its reading to the car by radio. Indirect systems use the anti-lock brake sensors to compare how fast each wheel spins. A low tire is a little smaller around, so it has to spin faster to keep up. U.S. federal rules require the warning when a tire is 25% or more below the car maker's recommended pressure.

distance per turn = π × tire diameter (a smaller tire turns more times to go the same distance)

Try it: Roll a big can and a small can across the floor for the same distance and count how many times each turns. The smaller can turns more times, just like a low tire. Measure each can's diameter and multiply by 3.14 to predict how far it rolls in one turn.

Keep learning: Science

Teaching it to your kids

Make flash cards from the symbols in your manual: red ones in one pile, yellow ones in another.
On the next drive, have your child watch the lights come on and go out during the bulb check.
Play “what would you do?” with each red light.
Show them where the warning light pages are in the manual.

Tips

A loose or broken gas cap can turn on the check engine light. Tighten it; if that was the problem, the light may go off after several trips.
The tire pressure light warns only when a tire is well below the right pressure, so keep checking tires monthly.
Notice whether a light is steady or flashing. That can change what it means.
Keep the owner's manual in the glove box.

Common mistakes

Mistake	Instead
Ignoring a yellow light for months	Yellow means check soon. Look it up and get it looked at.
Driving on with a red oil pressure or temperature light	Pull over safely and turn off the engine. Driving on can badly damage the engine.
Guessing what a symbol means	Look it up in your owner's manual, since symbols vary by car.
Driving with the parking brake on	Make sure the brake light goes out before you drive.

Safe habits

Treat red lights as urgent and pull over when it's safe.
Don't drive with the brake light on if the brakes feel wrong or fluid is leaking.
Avoid driving with a flashing check engine light.
Let an overheated engine cool before checking anything.

When to call a pro

A flashing check engine light: avoid driving until a technician repairs it.
A brake light that stays on with the parking brake off, plus a leak or brakes that don't work right: don't drive; have the car towed.
An oil pressure light that stays on after adding oil: have the car inspected before driving on.
A charging system light: have the alternator and charging system checked soon.

Sources

Free how-to guides for families, with nothing to earn, pass or send in. They follow U.S. rules and sources; your owner's manual, product labels and state and local rules come first.

🚨 Read Dashboard Warning Lights

Name ____________________ Date __________

You'll need

Your car's owner's manual (the warning light section)
A few minutes in the parked car

Steps

Open the manual. Find the warning light section in your owner's manual. Symbols and meanings vary by car, so your manual is the final word.
Learn the colors. Red means a problem that needs attention right away. Yellow or amber means something needs checking soon.
Watch the bulb check. Turn the ignition to ON without starting the engine. Several warning lights glow, which shows they work. Lights like oil pressure and check engine should go out once the engine starts.
Check engine light. A steady light means the car's computer found a possible problem, often with emissions. Make sure the gas cap is tight; if the light stays on, have the car checked. If it flashes, the problem could cause serious damage, so avoid driving until it's repaired.
Oil pressure light (red). Oil pressure is low. Pull over as soon as it's safe, turn off the engine, and check the oil level. If the light stays on after adding oil, don't keep driving; have the car inspected.
Temperature light (red). The engine is overheating. Pull over when it's safe, turn off the engine, and let it cool before checking coolant or calling for help.
Battery or charging light. The charging system isn't working right; it could be the alternator or its belt, not only the battery. Get to a repair shop soon, before the battery runs down.
Tire pressure light. One or more tires are well below the right pressure. Check and fill them. If the light flashes for about a minute and then stays on, the monitoring system has a problem.
Brake light. It comes on when the parking brake is set. If it stays on after you release the parking brake, the brake fluid may be low or the brakes may have a problem. Stop in a safe place; if you see a leak or the brakes don't feel right, don't drive. Have it towed.

Safe habits

Treat red lights as urgent and pull over when it's safe.
Don't drive with the brake light on if the brakes feel wrong or fluid is leaking.
Avoid driving with a flashing check engine light.
Let an overheated engine cool before checking anything.

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