Dashboard warning lights: what do they mean?

Few things are as unsettling as the sudden illumination of one of those colorful little lights on our dash. Because that usually means trouble. But most of the time it’s hard to know what kind of trouble, exactly.

On top of that, when it really comes down to it… how many of us actually know what all those lights mean? (I’m more of a car geek than most of the population, and I was surprised to realize that I wasn’t really sure about several of them.)

Most of us have the same basic set of dash lights in each of our cars. Some cars might have some additional ones, but in general we all have:

Seat belt

This one is easy. We all have it, we all know to do it, and most of our cars probably have a very obnoxious, incessant chime, just in case we ever somehow forget to put our seatbelt on.

Oil

Seeing this? Better stop and see what’s going on.

Except it doesn’t look like any oil vessel we can think of. Certainly not like a motor oil bottle. Or a Tin Man-style oil can. Or a barrel-like drum. In fact, it looks more like a gravy boat with a lid. But apparently oil cans did look sort of like that, years ago… at least if you had a Bentley. (Here’s a very fancy one on an auction site!)

But if the one on your dash lights up, it means your oil pressure is low. And that can be very serious. So it’s best to pull over as soon as you safely can, and check the oil level, being careful not to touch any metal parts of your car’s engine, since it will have been running and could burn you. If the oil level is low, do not drive the car—driving without enough oil can cause serious, permanent damage to your car’s engine.

Bentley vintage oil can (image credit: AntiquesAtlas.com)

Airbag

This one could mean trouble. It’s telling you that something’s amiss with your airbag system. It’s important to get this checked out, because you definitely don’t want to drive around with one of your key safety features possibly out of commission.

Antilock Braking System

Like the airbag, ABS is one of the most critical safety advancements in the past few decades. If this symbol is lit, it means your ABS system needs attention, and could potentially fail. 

Please note that this doesn’t mean your brakes won’t work, just that the technology that helps your brakes stop more effectively, without locking up, so that you don’t skid.

Engine temperature

If you see this, your engine is overheating.

This is the one that looks sort of like an old-school mercury thermometer floating on the ocean. It’s hard to say exactly what those waves are supposed to be. But the thermometer part is pretty clear: when this light comes on, it means your engine is overheating.

Yikes! 

This can be a serious problem, and you’ll want to pull over as soon as you safely can. Preferably in the shade. Turn the car off and let it cool down. At this point, please do not unscrew the radiator cap—there’s a lot of scalding liquid under very high pressure in there. Let it sit for 30 minutes or more. Then, put a rag over the cap and very slowly unscrew it just enough that you hear some pressure release. Then, slowly unscrew it the rest of the way.

If your coolant level is low, inspect all the hoses, water pump, and radiator itself. Look for anything that looks cracked or damaged. Then add more coolant. If you haven’t identified the source of the leak, and/or don’t know how to fix it, you’ll want to take it to a qualified mechanic.

Traction control

It looks like skidding, but if this symbol is lit, it’s
actually preventing you from skidding!

This symbol is a little confusing, because it looks like a car skidding out of control. But really, it’s kind of the opposite—it’s showing you that the traction control system is active, to keep you from skidding out of control.

(If your car doesn’t have traction control, you of course won’t see this one on your dash.)

Gas light

We definitely all know this one… 

Battery

There’s more to the battery light than what most of us might initially think of: our battery is low. That’s actually not what it’s telling us. When this light’s illuminated, it means there’s a problem with the system our car uses to charge the battery. 

See, your car’s battery (if you have a gas-powered car)  is sort of like a rechargeable battery in that every time we drive, it gets charged up by energy from the engine. Mostly it’s the alternator. So this light usually means there’s something up with some part of the alternator. Often—and this is a relatively easy fix—it’s the alternator belt.

Washer fluid

This is one of the simplest lights—it simply means that the windshield washer fluid is low and needs to be refilled.

Low tire pressure 

Uh-oh! One or more of your tires is not as inflated as the others.

Okay, I kind of hate this one. It’s useful to alert you to a flat, near-flat, or low enough to be a concern tire. But I find that a lot of times this light is overly alarmist. On cold mornings, it seems to almost always light up, and then goes out once the tires warm up a little and the air in them expands and everything’s okay again on the tire pressure front.

Likewise, mine seems to go off at the slightest disparity. One of my tires will be 1-2 pounds lower than the others, and there it is, sounding the alarm.

But for those times when you discover you have a slow leak because there’s a roofing nail in your tire, so you can go get it patched before driving a long distance and potentially getting stranded… it’s pretty useful.

Check engine

The infamous check engine light could mean so many things.

The problem with the check engine light is that it could mean anything. Or nothing. It’s just one symbol for hundreds of things that could be wrong. Here are some of the more common reasons for it to light up:

The simplest cause to fix is a loose gas cap. A lot of cars have a sticker or imprinted words on the fuel door or the gas cap telling you to turn clockwise until you hear two or three clicks. This is basically a way to make sure the gas cap is on tight enough to seal properly. When it doesn’t—or any other part of the system isn’t properly sealed—you might get a check engine light. Luckily, this one is an easy fix: if you tighten the gas cap, the light will go off after a bit of driving, if it was in fact the culprit.

Probably the most common cause of a check engine light is a problem with the oxygen sensor. The sensor optimizes the fuel-to-air ratio. If it’s not working properly, you’ll get the check engine light. This one isn’t too expensive to fix, fortunately. Repair costs average around $200.

One of the most expensive (and also somewhat common, unfortunately) check engine light-triggering problems is a catalytic convertor that needs replacement. That typically costs around $1,200. 

Keeping your car current with the manufacturer’s recommended maintenance schedule is the best way to hopefully prevent any of those lights on your dash from illuminating. Make sure you have a mechanic you trust, and try to follow their recommendations to keep your car running safely and reliably.

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