We know the feeling.
You're having a peaceful drive, minding your own business, and then all of a sudden your dashboard lights up like a Christmas tree.
But cars have feelings too, and they're going to tell you when something doesn't feel right.
Trouble is . . . you might not know what a certain symbol means.
Warning Lights: Colour Code
Much like traffic lights, dashboard warning lights follow a 3-colour system, depending on urgency.
-
Green/Blue – Informational: Strictly speaking, not a warning light. It's just telling you that the system is currently in use and working correctly. Nothing to worry about.
-
Yellow – Action required: Something isn't working the way it should, and whilst you don't need to act now, it should be checked when you get the chance.
-
Red – Urgent: There's a serious, potentially dangerous issue, and you'll often have to stop driving then and there.
So, moral of the story: you can get away with green and orange dashboard warning lights, but ignore red ones at your peril.
Oil Pressure Warning Light
One of the most serious warning lights you can get. Whilst no warning light should be ignored, the engine oil pressure light is especially important to take note of, as oil pressure is generated by the oil pump in order to keep the engine circulating.
It could be a simple case of topping up the oil level, but if that doesn't work, it could signify low oil pressure or a problem with the oil pump, possibly resulting in huge repair bills or even a write-off.
Safe to drive?
No.
Stop and check your oil level at the soonest opportunity.
Brake System Warning Light
This brake warning light shouldn't be ignored, and generally requires urgent attention. It could just be that you've left the handbrake/parking brake engaged when pulling away, so check and make sure that it's fully released (some cars have the letter 'P' to represent it).
Or the brake system warning light could mean that the brake fluid level is too low and needs topping up or that the brake pad wear sensor is faulty. However, it could also indicate a more serious problem with the braking system. For example, if you press the brake and it feels spongy or sinks all the way to the floor, then it's a sign that a major issue has occurred.
Safe to drive?
It depends.
If the brake fluid level's topped up and the pedal doesn't feel spongy, then a faulty sensor might just be showing up the brake warning light, in which case it's safe for you to drive to a garage.
But if the pedal doesn't feel right, your hydraulic brake circuits may have failed. In that case, pull over and get help.
Check Engine Light
Another of the more important warning lights. Even if driving still feels normal, the light could warn of potential damage to the engine so it's very important to get your car checked, even if it feels completely normal to drive. In short, a warning light that you want to avoid at all costs.
Safe to drive?
It depends.
If the light is steady and not flashing and there's no loss of power, then you should be good to go until it's checked.
But if the light is flashing, then avoid driving and high engine speed. Stop the vehicle at a safe place. Restart the engine after 2 minutes to reset the engine management system. If the light is still flashing, then turn off the engine.
How Long Can I Drive With My Check Engine Light On?
For as long as you can chance it and the vehicle clunks to a stop.
Just joking . . .
Generally, it's safe to drive for around 50 to 100 miles with the light on.
Low Tyre Pressure Warning Light
For the past few years, it's been compulsory for automakers to fit tyre-pressure monitoring systems in their cars, so they're increasingly common on UK roads.
Essentially, if low pressure is detected in any of the tyres, the system will provide a warning. Which is important as low pressure can negatively affect cornering and braking, or in serious cases even cause a blowout at high speeds. If the system alerts you to low pressure, you’ll need to check and inflate the tyre. If it has an obvious puncture, you’ll need to change the wheel or use a puncture repair kit.
Safe to drive?
Yes, unless there's an obvious puncture. However, you should take a little more care than you would normally, and aim to put air in the tyre at the soonest opportunity.
Anti-Lock Brake System (ABS) Warning Light
The anti-lock braking system is the amazing invention that lets you brake and turn sharply at the same which would otherwise cause the wheels to lock. It can really come in handy whenever you want to make an abrupt stop or when driving in difficult conditions.
Safe to drive?
Yes, as long as there aren't any noises coming from the wheels. But check your vehicle handbook just to be on the safe side. In any case, extra care should be taken when driving if you see the ABS warning light, especially during icy or wet weather, as your car's braking distance may have increased.
Diesel Particulate Filter Warning Light
A diesel particulate filter is fitted onto diesel cars in order to capture and store exhaust soot (some refer to them as soot traps) to reduce harmful emissions.
In order for the filter to work effectively, the vehicle has to be driven at motorway speeds on a regular basis, so if the warning light comes up, it could be a sign that you've been doing too much stop-start driving.
Safe to drive?
Yes, but you'll have to drive for around 10 minutes at 40mph or above as soon as possible in order to clean out the filter.
Low Fuel Warning Light
Fairly self-explanatory, but we'll go through it anyway . . .
When your fuel reaches below a certain level (usually around 50-70 miles remaining), this warning light will come on.
Running out of fuel isn't illegal in and of itself and won't cause any lasting mechanical damage, but it could force you to come to a stop on the road – which is an offence.
If you run out of diesel, then it's necessary to bleed the air from the injectors and fuel lines before the engine will start properly, which means more than simply topping up from a jerrycan.
Safe to drive?
Yes, but only until you get to a fuel station. Don't leave it off for too long.
Airbag Warning Light
Yes, the airbag warning light might look like somebody balancing a massive beachball on their lap, but it's really more sinister as it means that one of the airbags is malfunctioning. It could inflate without warning whilst you're driving or not inflate at all in the case of an accident, and then you'd be in trouble.
Safe to drive?
No.
Although there's no legal requirement to drive with an airbag installed, it's an incredibly important fail-safe that has the power to save your life.
Engine Temperature Warning Light
If you see this light on at any time after starting up, then it means that the engine is either running too hot or there isn’t enough coolant in the system. It could also be due to a faulty water pump or that the car's radiator is clogged, leaky or broken – all of which can leave you in a nasty pickle.
Even more serious is a blown head gasket (signalled by white smoke coming from the exhaust), which could signal catastrophic failure if the engine isn't turned off immediately.
Safe to drive?
No.
This is something that requires urgent attention.
Power Steering Warning Light
You probably don't know you even use a power steering system, but you'd struggle to turn your steering wheel if it didn’t have it. It's basically a hydraulic or electric pump that helps to turn the steering. Which means that when the warning light for the system illuminates, you'd better take it seriously.
Safe to drive?
Yes, but you may notice that the car becomes harder to manoeuvre when this warning light appears, meaning extra care should be taken. Driving at high motorway speeds without power steering assistance can prove particularly hazardous.
Battery Warning Light
This can indicate a number of things, all relating to the car’s charging and battery system. This could prove dangerous during night-time driving, since a failing battery can lead to headlights failing, but without the charging or battery system providing electricity, you may also find that the brakes, the power steering or even the engine itself stop working.
Safe to drive?
No. Because the battery isn't charging, you're advised to have the fault looked at immediately.
Seatbelt Warning Light
The vast majority of modern cars come with a system that lets you know if you or any of your passengers haven’t got their seatbelts fastened. If this is the case, a light will flash along with a possible sound.
Safe to drive?
No. The law states that you must wear a seatbelt unless you qualify for a medical exemption and have a certificate to prove it.
How to Reset or Turn Off Car Warning Lights
So, you've gone to a garage or called out a mobile mechanic, and the problem relating to the warning light has been fixed.
But what if the light still stays on?
That's usually because the mechanic forgot to reset your car's onboard computer, which can be done by opening and closing the bonnet and turning the vehicle on then off.
However, if it still remains on, in some cases you may need to disconnect and then reconnect your battery. Or take the car for a drive so that it will reset itself.
If the warning light still remains, the mechanical problem might still be there, or there could be another one that's impacting your vehicle.
Summary
You're now hopefully well-informed to know when car dashboard warning lights need addressing and what the different symbols mean.
Just don't ignore the red ones!
FAQs
What do car dash warning symbols mean?
Green/blue dashboard warning lights let you know that a system is on and aren't anything to worry about. Orange/yellow warning lights let you know that there's an issue which needs checked, but not immediately. Red warning lights let you know that an issue needs urgent attention.
What is the most serious warning light?
The check engine light is typically the most serious of car warning lights due to the kind of damage it can signal. Sometimes, if left unchecked long enough, your engine can suffer some serious damage.
Can I drive my car with warning lights on?
Often yes, but this should generally be avoided. In particular, you should try to avoid using your car very often or travelling long distances whilst your engine management light is on and before it's received a diagnostic check.