Every time you start your car, all those lights on the dash come on and then, after a few seconds, they all go off again… except that sometimes they don’t.
What options your car has and what it is capable of warning you about varies from one car to another, but there’s a core set of warning lights that are common to most modern vehicles. Some of them are gentle reminders of things you'll need to attend to eventually, some of them are merely informational only, and some are extremely serious and mean you should pull over and shut off the motor as soon as it is safe.
Do you know which is which? Do you really know what they all mean? Gadgets and gizmos vary from one car brand to another, but there is a set symbols that you’ll find almost everywhere. We’ve broken them down into sections so that you know just what you’re dealing with – and what you need to do next when one lights up!
Stop the car!
These warning lights are serious. You or your car are at serious risk, and you should pull over and shut off the engine as soon as it’s safe to do so. Depending on the issue, some of these lights may indicate you need to call a tow truck or roadside assistance, because even if possible continuing to drive would be dangerous.
Check Engine Light (CEL)/Malfunction Indicator Light (MIL)
With the introduction of the OBDII system (onboard diagnostics, version 2) this light appeared in every car and even on some motorcycles. If it is flashing it indicates a serious problem and you should pull over and shut the car down as soon as it is safe. When it lights up, it means the computer electronic control unit (ECU) has detected a problem in the engine or emission controls systems. The problem could be mechanical, or electronic, or could even be nothing more than a sensor going bad; you won't be able to tell without a code reader, but you should stop as soon as possible to investigate
This light indicates an issue with the brakes or the anti-lock braking system (ABS), and obviously it can be unsafe to drive if the brakes are compromised. If it is an ABS issue, the car may be able to be driven, but you lose the added safety of ABS in a panic stop, and if it is a bad ABS sensor, you may lose stability and traction control as well. The brake light may also light for a low fluid condition, or an emergency brake that has been left engaged.
Power steering failure
Modern cars use power steering, with an electric assist or hydraulic assist, without which it takes considerable effort to steer at lower speeds. Nearly every vehicle now uses rack and pinion steering, which has lower mechanical advantage than older systems, but quicker ratios. Without power steering a car can still be driven safely, but it will take considerable strength to steer; emergency maneuvers might be effected.
This indicates a fault with the airbag system, also know as the supplemental restraint system (SRS), which does not affect the way the car drives or handles but could be very serious if you are involved in an accident. Driving with extra caution is suggested, but you should be safe to continue on to home or work. A variation of this light could light to indicate the passenger side air bag has been deactivated, manually or because a baby seat is detected.
This old style oil fill jug indicates something in the engine oil is below optimal. Similar lights can mean oil pressure, oil level (with a wavy line), or oil temperature (with a thermometer). When this light is red it means that there is not enough oil pressure in the engine to circulate the oil and prevent wear. Pull over and shut off the car immediately to prevent engine damage. If the light glows amber, it is less serious, but still means you need to check and possibly add oil as soon as possible.
Typically when this light glows red it means your car is getting close to overheating, which can cause serious damage if you continue to drive. If this light comes on red soon after starting the engine, it likely indicates the coolant level is low. Some cars light the same light in blue when the car is cold to remind you to drive less aggressively until the engine is fully warm.
If one or more doors are not properly latched, you should stop and fix it as some as it is safe to do so. This is probably the most obvious problem and the simplest to solved, and we don't have to explain why it is so dangerous it needs a warning light.
Slightly less dangerous than a door being unlatched, the hood or trunk/hatch coming open while driving is still a safety issue. Most modern cars will now warn you before a dangerous situation happens, like a hood blocking your view of the road.
Not every warning indicator on the dashboard is something serious that you ought to be concerned about. Many are just reminders to perform ordinary maintenance tasks.
General service reminder
The computers in cars today keep track of general driving conditions, and mileage, to be able to remind you to have your car serviced periodically. Often times an amber or red wrench will appear, or the words "service engine soon", to let you know that it is time for an oil change or other service. Which service and how frequently differs by make and model, and if you follow our accelerated service plan you will find yourself resetting this light frequently before it is even activated.
Tire Pressure Monitor System (TPMS)
Tires lose air over time, and the pressure can also be affected by a drop in ambient temperature, which can affect handling, braking, and fuel economy. For these reasons modern cars have small electronic monitors in the wheels which will warn you on the dash if a tire is off by as little as 5 psi. Typically this isn't cause for alarm, but a TPMS light can indicate that you have run over something and a flat is imminent.
Loose gas cap
Modern emissions are so strict that the fumes evaporating out of an open gas cap can be several times more unburned hydrocarbons that what comes out the tailpipe. For this reason cars now have sealed systems, and will alert you if a leak is detected. Typical it is just a matter of undoing the filler cap and screwing it back in until it clicks.
Low fuel warning
Most of us keep a pretty sharp eye on the fuel gauge, but the fuel warning light is a useful reminder that you’re on borrowed time. Depending on your car you may have 15-30 miles worth of fuel in the tank – your car’s owner's manual may tell you how much range you have left before you have to get out and push, or many cars these days will start counting down estimated range when the light comes on.
Diesel exhaust fluid (DEF)
Few diesel cars are sold in North America, put plenty of diesel pickups are, and they have their own specific warning lights, the most important of which is the DEF light. DEF is the blue fluid injected into diesel exhaust to fight pollution, and if you run out your truck will go into limp mode or may not start. When this light is lit, fill up the blue diesel exhaust fluid tank at the next fill up.
Key fob missing/battery low
With new proximity keys, you no longer have to put the key into the slot to start the car, but you do need a key fob with a good battery in it. If the battery goes dead you may not be able to start the car, or there may be a manual back up, but your car should give you plenty of warning before that happens. This light will also warn you if you try to drive it without the key, if for instance, the passenger gets out and takes the keys with them. Pay attention! Many cars will allow you to drive for miles before immobilizing themselves, stranding you miles from the keys.
Do you need to be told when your headlights are on? On cars with daytime running lights (DRL), it can be hard to tell if your actual headlights are on. This can be dangerous as the DRL are not as bright as the actual headlight. To counter this, most cars now have a green lantern shape to indicate your lights are on, or sometimes an indication that they are on "auto". This can look similar to the high beam indicator, but is green instead of blue.
You can go days and weeks without using the windshield washer, so it’s easy to be surprised when the reservoir needs filling up. Washer fluid is more important than it seems, as anyone who has suddenly found themselves driving into the setting sun with a dirty windshield can attest to.
These are some other warnings you might see, but typically they mean you have a problem, not the car.
Parking brake on
As mentioned at the top, if you leave the parking brake on you will get a warning, long before the smell of burning brakes that comes a few miles later. This may be a red circle with a "P" in the middle, or it could just be a multi-purpose brake warning indicator.
This needs no explanation, we all know we should buckle up for safety, and if you don't your car will remind you with a light and a beeping alarm.
As for the rest…
We couldn’t include every single warning lamp on every single car model, so we’ve stuck to the really important ones that could make the difference between dangerous driving, expensive repairs or a ticket from law enforcement officers.
You have been warned. (Ahem.)