What do the different dashboard warning lights mean

Dashboard warning lights

As cars have evolved the amount of different dashboard warning lights in your vehicle has increased greatly. Modern electrical systems such as airbags or stability control are often self-testing to make sure they are sure they are still working correctly. So it makes it very important to know whether the warning light you are seeing on your dash requires you to come to us immediately for the fault to be fixed or whether to continue your journey and come to us later.

If a warning light comes – or if it fails to extinguish once the engine has been started you should stop the car in a safe place. In many cases the warning lights that you see on the dashboard can be model and car specific. The vehicles handbook will give you a better detailed explanation of their meaning and what action you need to take.


Oil pressure warning light

The oil pressure warning light will show when the ignition is turned on and should immediately turn off once the engine starts.

If the light stays on once the car is in motion or illuminates during your journey you should stop the car, switch off the engine, wait for it to cool and then check your engine oil level.

Top up the engine oil if the level is low.

If once you have topped the oil up and the oil pressure warning light is still showing on your dash you should not start the engine and seek assistance.


Battery charge warning light

This light will show up on your dashboard when the ignition is switched on and should disappear once the engine is started

If it doesn’t illuminate when you turn on the ignition – or if it illuminates whilst you are driving; it means the battery is not being charged as there is a fault with the cars charging system.

This could be due to one of the following reasons:

  • Broken or loose alternator drive belt
  • Loose battery or starter terminal
  • An alternator failure

If your drive belt is broke it needs to be repaired before you can start the engine. Your cars coolant system may rely on this belt and driving with it broken could cause the engine to overheat, therefore causing further damage to your engine.

You should move the vehicle to a safe location and turn of the engine. Do not restart the car and seek assistance.


Brake system warning light

This light should remain on the dashboard when the handbrake is engaged. If it stays on once the handbrake is released it could indicate low brake fluid level.

Check the vehicles handbook and top up the brake fluid to the correct level up to the MAX marker. As your brakes wear the fluid level will gradually drop. Check the brake fluid level regularly to make sure there is no further loss of fluid.

If the brake fluid is too low and brake pedal travel is distinctly longer than usual, one of the two hydraulic brake circuits may have failed. Do not continue your journey and seek assistance.

If the brake system warning light remains on – even though the brake fluid has been topped up this may indicate a fault with your sensor. Take your vehicle to us and we will diagnose the problem.


Diesel Particulate Filter (DPF) partially blocked

Diesel Particulate filters (DPF) catch bits of soot in the exhaust.

Think of the Diesel Particulate filter similar to the bag in your vacuum cleaner that has to be emptied often in order to maintain performance. In a DPF it is called regeneration – meaning that the soot is burnt off at a high temperature and only leaves a small ash residue. This regeneration can be either active or passive.

Passive regeneration will take place automatically on longer journeys when the exhaust temperature is high. So people don’t often use their cars on longer journeys regularly so the manufacturers have fitted an ‘active’ regeneration when the car’s engine management computer (ECU) takes control of the process.

When the soot built up in the filter reaches a certain limit – normally around 45%, the ECU can make some small amendments to the fuel injection timing to increase the exhaust temperature and begin the regeneration process. If it is a stop / start journey the regeneration will not happen and the warning light will continue to show the DPF warning light.

You should be able to begin a complete regeneration and clear the warning light by driving for 10 minutes or so at speeds greater than 40mph.


Engine warning light

The engine warning light illuminates once the ignition is turned on. Once the engine starts it should switch off.

It is continues to show when the engine is running it shows an issue with the engine management system. This needs to be checked as soon as possible

If the engine warning light flashes whilst you are driving you need to reduce the speed of your vehicle immediately until the light shows constantly. If it continues to flash, slow down your vehicle, avoid high engine speed and heavy acceleration and then stop the vehicle and have it checked straight away.

On some vehicles this light could be red – again you must stop your vehicle and seek assistance.

If you have parked in a save place switch off the vehicle, leave it for a couple of minutes and then restart the engine in order to reset the engine management system

Once the light is illuminated the vehicle is still safe to drive as long as there are no other faults with the engine. Take your vehicle to us as quickly as possible to avoid any damage to the catalytic converter and have any repairs undertaken.


ABS warning light

When the ignition is initially turned on, the light will briefly illuminate to confirm that the system is working.

If you have started driving and it illuminates it indicates a malfunction – it needs to be checked as soon as possible.

Normal braking with your ABS can generally be maintained and most cars will be safe to drive – although it is important to check your vehicles handbook for further advice.

Take your vehicle to us to double check the fault as soon as possible.


Brake system and ABS warning lights

If both warning lights illuminate at the same time when driving, stop the vehicle as soon as it is safe to do so.

Reduce vehicle speed slowly and immediately move the vehicle to a safe location. Use the brakes with great care. Do not step on the brake pedal abruptly. Seek assistance.


Fuel filter water trap (diesel engines)

The Fuel filter water trap on diesel engine should illuminate once the ignition is switched on and should turn off after a few seconds.

It is turns on one the vehicle is in motion it show that there is water in the fuel filter. The light being illuminated shows that the amount of water in the fuel filter had reached the specified level. Normally the vehicle is safe to drive – but the water in the fuel filter needs to be drained as soon as possible.

If you have just re-fuelled your vehicle – move it to a safe location and turn off the engine. The fuel may have been contaminated and may cause damage to the injection system.

All your diagnostics and coding issues can be fixed in our Newport showroom and workshop. Call us on 01633 276682 or come down to the Leeway Industrial Estate, Newport, South Wales, NP19 4SJ