Few things make a driver's heart sink quite like a warning light glowing on the dashboard halfway along the A2. Some are harmless reminders, others are telling you to pull over before you do expensive damage. Knowing the difference is one of the simplest skills you can build as a motorist, and it can save you hundreds of pounds in repairs.

What the colours actually mean

Manufacturers follow a rough traffic-light system, and it is worth learning before anything goes wrong.

• Red — stop as soon as it is safe to do so. Something serious is wrong, and carrying on risks destroying an engine, gearbox or braking system.
• Amber or yellow — something needs attention soon. The car is usually still drivable, but get it looked at rather than waiting for it to become a red light.
• Green — information only. Sidelights, indicators, cruise control, lane assist.
• Blue — normally a reminder, most often that your main beam is on and could dazzle oncoming traffic on unlit lanes.

Red lights: stop safely and switch off

If the oil pressure light (a dripping oil can) appears, pull over at the first safe opportunity and stop the engine. Running an engine with no oil pressure can wreck it in minutes. Check the dipstick once the car is level and cool enough to touch.

The coolant temperature warning (a thermometer sitting in waves) means the engine is overheating. Stop, let it cool, and only then check the expansion tank. Never unscrew a hot coolant cap — scalding steam escapes under pressure.

If the battery or charging light comes on while you are driving, the alternator has probably failed and you are running on stored battery power alone. Turn off the radio, air conditioning and heated seats, and head for a garage or a safe place to stop — your lights and power steering may fade.

A red brake warning light with the handbrake fully released should be treated as urgent. Brake fluid may be low, or there may be a fault in the system. Do not simply top it up and carry on; a leak needs investigating.

Amber lights: book it in soon

Amber is the "don't panic, but don't ignore it" zone. The most common is the engine management light, a small engine outline. If it is steady, the car is usually safe to drive gently, but arrange a diagnostic check within a few days. If it is flashing, that is a different matter — it often signals a misfire that can damage the catalytic converter, so slow down and stop as soon as you safely can.

Other amber lights worth knowing:

• ABS — your anti-lock braking is disabled. Normal brakes still work, but leave extra stopping distance, especially in the wet.
• Tyre pressure — check all four tyres and the spare at a garage, ideally when the tyres are cold.
• DPF (diesel particulate filter) — often caused by too many short trips. A steady 20-minute run at motorway speeds can help it clear.
• AdBlue — top up soon; many cars refuse to restart once the countdown reaches zero.
• Traction control — usually safe to drive, but be gentle on greasy roundabouts.
• Airbag or SRS — the system may not deploy in a crash, so get it seen to.

Green and blue lights: reminders, not warnings

These are the reassuring ones. Green tells you a feature is switched on — headlights, front fog lights, cruise control, stop-start. Blue almost always means main beam. If you are following another car or passing through a lit stretch of the A2, dip them. There is no fault here, just a nudge about courtesy and visibility.

Kent roads that are hard on your car

Driving around Gravesend and the wider county puts particular strain on certain systems. The stop-start crawl through Gravesend town centre, up to the Dartford Crossing and along the M2 approach punishes brakes, clutches and batteries. Rural lanes around Meopham, Shorne and Cobham are full of potholes and crumbling edges that knock tyres and tracking out of alignment — a tyre pressure light after a bump is worth taking seriously.

Coastal and estuarine air, plus winter gritting, encourages corrosion on brake lines and suspension components. And if you mostly do short hops to the shops, a diesel will clog its DPF and a petrol car will sap its battery. A longer run once a fortnight does more good than most people realise.

What to do when a light appears

• Stay calm, indicate, and find a safe place to stop — not the hard shoulder unless it is a genuine emergency.
• Check your handbook for the exact symbol. Shapes vary between makes, and a symbol you assume is "just the engine" may be something else entirely.
• Note anything unusual: noises, smells, a drop in power, a spongy brake pedal. It helps a mechanic enormously.
• Check oil and coolant only when the engine is cool.
• Do not disconnect the battery to clear the light before a garage reads the fault codes — you will erase the evidence.

Keep a tyre pressure gauge, a torch, a hi-vis vest and a litre of oil in the boot. Ten minutes of preparation on a Sunday afternoon is far cheaper than a recovery truck on a Friday evening.