Dashboard Warning Lights: Keep Driving, See a Mechanic or Stop?
Not every dashboard warning light is equally urgent: some are just for information, others send you to the garage and a few mean you have to stop. Here's how to tell them apart and what to do about each one.
The colour code: a traffic light on your dashboard
Your dashboard uses a traffic-light colour code shared by most manufacturers. Knowing it helps you work out how much time you have.
Green and blue lights are for information only. Examples include dipped headlights, main beam and cruise control. Amber lights mean something is wrong, but you can still make it to a garage. Red lights mean you should stop as soon as it's safe to do so.
Amber warning lights: something's wrong, but you can reach the garage
Steady engine warning light. The ECU has stored a fault code, often related to emissions. A pocket OBD scanner will tell you which one it is before you go to the garage.
Tyre pressure. This is the horseshoe with an exclamation mark. It often comes on the first cold autumn morning: cold air takes up less space, so pressure drops even if the tyre is fine. Inflate the tyres when cold and, on many cars, reset the system from the menu. If you don't, the light will stay on.
ABS. If it comes on, you haven't lost your brakes. You brake just the same, but in an emergency stop the wheels can lock and the car stops turning where you steer it. Until you reach the garage, leave a bigger gap to the vehicle in front.
Airbag. Depending on the manufacturer, it may be amber or red. It warns that the system may be deactivated. In a crash, the airbag may not deploy, and neither may the seatbelt pretensioner.
Watch out if the engine light is flashing
The engine warning light has two sides. If it flashes, for practical purposes it is no longer an amber warning.
Flashing means a cylinder is misfiring and unburnt fuel is reaching the catalytic converter, which can overheat and be damaged in a short time. Ease off and, if it keeps flashing, stop.
Red warning lights: stop as soon as it's safe
Engine temperature. This is the thermometer immersed in liquid, and it warns that the engine is overheating. If you can't stop yet, turn the heater up to maximum: the heater matrix draws heat away from the engine. Don't touch the cap while the engine is hot, because the system is under pressure.
Battery. It warns that the battery isn't charging, almost always because of an alternator fault. You're running on whatever charge is left in the battery. And if the belt has failed, on many engines it also drives the water pump, so temperature will be the next thing to cause trouble.
Brake. This is the circle with an exclamation mark. With the handbrake off, it usually indicates low brake fluid. If that's down to worn pads, you have some margin; if it's a leak, the pedal may go to the floor. You can't tell which from the driver's seat, so treat it as a leak.
Oil pressure. This is the Aladdin's lamp. It measures oil pressure, not oil level: you can have a full sump and a pump that isn't pushing oil round. If it comes on while you're driving, parts may be rubbing together almost dry. Switch the engine off immediately. Carrying on to the next exit usually costs more than the tow truck.
The ignition test: key when buying a used car
When you switch on the ignition without starting the engine, the warning lights come on to show they're working. If you're buying a used car, pay attention at that moment.
If the airbag light never comes on, someone may have disabled the warning to hide a fault. The same goes for the engine and ABS lights: if they don't appear, ask why.
In short: the colour tells you how much time you have, flashing tells you that you have less, and the light that doesn't come on when you switch on the ignition may be the one hiding the most.
Frequently asked questions
Can I keep driving with the engine warning light on?
If it's steady, you can get to a garage, because it indicates a stored fault code. If it's flashing, ease off and, if it doesn't stop flashing, stop.
Why does the tyre pressure warning light come on in cold weather?
Cold air takes up less space, so pressure drops even if the tyre is fine. Inflate the tyres when cold and, on many cars, reset the system from the menu.
What should I do if the Aladdin's lamp light comes on while driving?
Switch the engine off as soon as it's safe, because parts may be rubbing together almost dry. Carrying on to the exit usually costs more than the tow truck.
Will I lose my brakes if the ABS warning light comes on?
No, you brake just the same, but in an emergency stop the wheels can lock. Until you reach the garage, increase the gap to the vehicle in front.
Informative article written with the help of AI tools from the verified script of the video. The video is in Spanish.