What Do the Common Dashboard Warning Lights Mean?

Red generally means stop safely as soon as you can, and amber generally means get it checked soon. Check your handbook for the exact meaning of any symbol, as designs differ between makes and models.

Below are the lights drivers ask about most, in rough order of urgency, with what is safe to check yourself and what needs a garage. If several lights come on together, or the car feels different to drive, treat it as more serious and stop somewhere safe rather than pressing on to finish your journey.

Which warning lights mean stop driving?

Some red lights should never be ignored. The oil pressure light, usually an oil can, means the engine may not be lubricated, so pull over and switch off. The coolant temperature light means the engine is overheating, so stop safely and let it cool before checking the level.

The red brake warning can mean low brake fluid or a fault in the braking system, and the handbrake being partly on can also trigger it. If it stays on with the handbrake released, do not carry on driving.

• Oil pressure: stop and switch off
• Coolant temperature: stop and let it cool
• Brake system: stop if it stays on
• Battery or charging: head for safety promptly

What does the battery warning light mean?

The battery symbol does not just mean a weak battery. It usually indicates that the charging system is not working, often the alternator or its belt. The car is then running on battery power alone and will eventually stop.

If it comes on while driving, switch off unnecessary electrics and get somewhere safe or to a garage. If the belt has failed, you may also lose power steering assistance and the engine may overheat, so do not push on.

What does the engine management light mean?

An amber engine symbol means the engine control unit has logged a fault. It could be minor, such as a sensor fault or a loose fuel cap, or more serious, such as a misfire.

If it is steady and the car drives normally, arrange a check soon. If it flashes, or the car is juddering or losing power, reduce speed and have it looked at promptly because a misfire can damage the exhaust catalyst. A diagnostic scan reads the stored codes and shows where to look.

What about ABS, airbag and diesel particulate filter lights?

The ABS light means the anti-lock braking function may be unavailable, although normal braking usually continues. The airbag light means the airbag system may not deploy properly in a crash, which is a safety matter and an MOT concern.

On a diesel, a particulate filter light means the filter is clogging, often after lots of short journeys. A longer run at a steady speed can sometimes help it clear, but if the light persists, it needs diagnosis before it becomes a bigger problem.

How does a garage deal with a warning light?

We connect diagnostic equipment, read the stored fault codes and check live data. A code points to the area of the fault but does not name the failed part, so we carry out further testing before recommending a repair.

Cost depends on the fault found, the parts needed and how much testing is involved. Clearing the light without fixing the cause is not a solution, because it will come back. If you can, note whether the light was steady or flashing and what the car was doing, since that helps us decide where to begin testing.