A warning light popping up on the dashboard is never fun, but not all of them mean you need to pull over immediately. Some demand urgent action; others just need a trip to the garage in the next day or two. This guide covers the most common dashboard lights you will see in UK cars, what each one means, and exactly what you should do about it.
Red Lights: Pull Over as Soon as You Safely Can
A red warning light means something serious is going on. If one appears while you are driving, find a safe spot to stop as soon as possible and do not keep going until the problem has been checked out.
- Oil pressure (red oil can): Oil pressure has dropped to a dangerous level. Switch the engine off straight away because running it without proper oil pressure can wreck the engine within minutes. Check the oil level. If it looks fine, do not restart the car and call for help.
- Engine temperature (red thermometer in water): The engine is overheating. Pull over safely, turn the engine off, and let it cool down before opening the bonnet. Never take the coolant cap off while the engine is hot.
- Battery (red battery symbol): The charging system has stopped working properly. The car may keep running on stored battery power for a short while, but head to the nearest garage or pull over before the battery dies completely.
- Brakes (red exclamation mark in a circle): First, check the handbrake is fully released. If it is down and the light is still on, it could mean brake fluid is low. Do not drive until it has been looked at.
Amber Lights: Get It Checked Soon
An amber warning light means something needs attention, but it is not a stop-the-car emergency. You should get it looked at within a day or two.
- Engine management light (amber engine outline): This is the most common dashboard light and also the vaguest. It could be anything from a loose fuel cap to a sensor fault or an emissions problem. Driving a short distance to a garage for a diagnostic scan is usually fine.
- Tyre pressure (TPMS, amber tyre with exclamation mark): At least one tyre is noticeably under-inflated. Check and correct your pressures when you get the chance.
- DPF warning (diesel particulate filter): The DPF is getting clogged. A sustained run on the motorway often clears it, but if the light stays on, you will need a garage visit.
- Service reminder (spanner or wrench): Just a prompt that a scheduled service is due. Not urgent, but do not leave it too long.
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Get my free quote →A Closer Look at the Engine Management Light
The engine management light (EML) confuses more drivers than any other warning. It comes on when the engine control unit (ECU) logs a fault and stores a diagnostic trouble code (DTC). The light itself gives you zero detail about what is wrong. Only a garage with a diagnostic tool can read the stored codes and work out the actual issue.
Common triggers for the EML include a faulty oxygen sensor, a loose or damaged fuel cap, a failing catalytic converter, a dodgy mass airflow sensor, or an engine misfire. Some of these are cheap fixes; others are more involved. As a general rule: if the EML is lit steadily and the car feels normal with no other warning lights showing, it is usually safe to drive to a garage for a diagnostic check. But if the EML is flashing, pull over. A flashing engine management light typically signals a severe misfire that can damage the catalytic converter.
Green and Blue Lights: Just Keeping You Informed
Not every dashboard light is bad news. Green and blue lights are purely informational:
- Green flashing arrows: Your indicator is on and working.
- Blue headlight symbol: Full-beam headlights are active.
- Green headlight symbol: Sidelights or dipped headlights are switched on.
- Green cruise control icon: Cruise control is engaged.
If you come across a light you do not recognise, check your owner's manual. Every car uses slightly different symbols and colours, and the manual will give you the definitive answer for your specific model.