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Would you pass the dashboard warning light test?


Modern cars have an array of dashboard warning lights to let drivers know when something’s wrong. But do you take notice of them?

Dashboard lights

Many motorists don’t take the time to familiarise themselves with dashboard warning lights.

But ignore them at your peril as this could result in a costly trip to the garage at a later date - as well as the risk to your safety.

Haynes manuals have been helping motorists to look after their vehicles for more than 50 years.

Red means stop!

Matthew Minter of Haynes says: "There are an increasingly diverse range of warning lights and messages.

"Generally, red lights call for immediate action, amber for non-urgent attention, while green or blue are generally just for information."

You should refer to your car’s handbook or Haynes manual for details specific to your car.

But with the help of the car experts at Haynes we’ve put together this general guide to dashboard warning lights for all motorists – both young drivers and older drivers.

Red lights

These lights are red for a reason. Urgent action may be required, either to prevent damage or for your safety.

Red dashboard warning lights

Engine oil pressure warning

If this comes on when the engine is running, stop as soon as it is safe to do so and switch off the engine, then check the oil level.

If the level is low, top up before going any further. If the level is okay but the warning light doesn’t go out when you restart, stop the engine and call for assistance as you should not drive even a short distance with this light on.

Coolant temperature warning

Pay attention if this light comes on and/or the gauge is in the red zone.

Turn the heater on full - maximum heat, maximum fan speed - to disperse some heat. 

Stop as soon as it is safe to do so, switch off the engine and open the bonnet. 

Allow the engine time to cool, then check the coolant level.  If it is low, this is almost certainly due to a leak.

Topping up with plain water may get you out of trouble, but check the system thoroughly at the first opportunity.

If there is a big leak, you'll have to call for assistance.  Don't add cold water to a very hot engine as damage could result.

Battery charge warning light

This light shows that the battery is not receiving a charge from the alternator, perhaps because the alternator drivebelt has broken.

On some cars the belt also drives the water pump, in which case you will notice signs of overheating and must stop and call for assistance.

If there is no overheating it’s okay to drive on for a few miles until you can get the system checked out, but the battery will go flat eventually.

Brake warning light

This may serve as a warning that the handbrake is on, but if it comes on at other times it indicates low brake fluid level.

Stop at the first opportunity - bearing in mind that braking performance may be poorer than usual - and check the level. 

A slow fall in level is normal as the brake pads wear. The need for frequent top-ups can only be due to a leak, which must be found and corrected without delay.

Amber lights

These tell you that some action is required, but not necessarily immediately.

Amber dashboard warning lights

ABS warning

This means the anti-lock braking system is not working. Normal brake operation is unaffected but you could skid under heavy braking.

Sometimes this light comes on for no apparent reason.  If this occurs try stopping, switching off the ignition for a minute or two, then restarting.

If the light now stays out, everything is probably okay. If it keeps coming on then you need to get the system checked.

Low oil or coolant level

If this warning light or message display comes on stop and check the level within a few miles.

However, you should stop at once if there are signs of overheating and/or the oil pressure warning light comes on.

Top up if necessary and keep a closer eye on the levels in future.

Engine management (check engine)

This shows that there is a problem in the engine management (ignition and fuel injection) system.

Depending on what the problem is, the engine may run roughly or with reduced power, but you should be able to drive on until you can get the system checked.

As with the ABS light, it may come on occasionally for no apparent reason.

Brake pad wear warning

If this warning light or message display comes on it means that at least one brake pad is nearly worn out and you need to fit new pads without delay.

If the pads wear down to the metal you'll be alerted by a grinding noise which is hard to ignore.

At this stage braking performance is dangerously affected and serious damage may have occurred.

Tyre pressure warning

If the light comes on and there are no immediate signs of a flat tyre such as noise, a rough ride, vehicle pulling to one side, it's okay to drive on cautiously until you can check the pressures.

Motoring manuals

Haynes has recently launched its top 50 car and motorcycle manuals online, so you can access service and repair information on the move on your laptop, tablet or smartphone.

To view the range of printed and online manuals click here.


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