Warning Lights in Your Car: When to Stop Immediately

The colours in brief

This is the general logic manufacturers use. The exact meaning of a symbol is in your owner's manual and differs between makes and models.

Red lights that mean you should stop

• Oil pressure (oil can): oil pressure is too low. Without enough pressure, bearings and cylinder walls stop being lubricated, and engine damage can happen within minutes. Switch off the engine immediately.
• Coolant temperature (thermometer in waves): the engine may be overheating. See Engine overheating: what to do?
• Battery: usually a problem with the alternator or power supply. The vehicle may soon stall because the battery is no longer charging.
• Brake (exclamation mark in a circle): if it's lit with the handbrake released, there may be a lack of brake fluid or a loss of pressure. Braking performance can drop. Don't keep driving.

The flashing engine warning light

If the amber engine warning light stays on continuously, the engine control unit has detected a fault, for example in the emissions system. You can usually keep driving briefly, but should visit a garage soon. If it flashes, that's more serious: the catalytic converter can be damaged. Ease off the accelerator, stop, and consult a professional.

What to do when stopping

1. Indicate, switch on hazard lights, and coast to the next safe stopping place.
2. Switch off the engine; don't restart it just to check if the light has gone.
3. Put on a hi-vis vest and set up a warning triangle, if it's safe to do so. On the motorway, also get behind the crash barrier, see Breaking down on the motorway.
4. If you're unsure whether you can keep driving: don't. Transport to a garage is cheaper than engine damage.

If the light goes off again

Some lights only flicker briefly or go off after a restart. That doesn't mean the fault is gone. The control units usually store a fault code that a garage can read out. For red lights, have the vehicle checked before a longer journey regardless.

When towing is needed

• The oil-pressure or brake light is on and can't be explained
• The engine runs roughly, knocks, smokes, or smells burnt
• The vehicle loses power or steering and braking no longer feel right
• The battery light is on and there's still a long way to a garage

Electric and hybrid vehicles have their own high-voltage battery warnings. For such a warning, transport on a flatbed is the safe choice, see Towing an electric car.