A light on the dash is your car telling you something. Some can wait a few days. Others mean you should pull over now. This guide explains the most common warning lights, what they usually mean and what to do next.
What the colours mean
Most manufacturers use a traffic-light system:
- Red: a serious problem or safety issue. Stop as soon as it's safe and investigate.
- Amber or yellow: something needs attention soon. You can usually keep driving carefully, but book a check.
- Green or blue: information only, such as headlights or cruise control being on.
Symbols vary between makes, so always check your owner's handbook for your exact car.
Red warning lights: stop when safe
Oil pressure (oil can)
Oil pressure has dropped. Driving on can destroy an engine within minutes. Stop, switch off and check the oil level. If it's full and the light stays on, don't drive.
Engine temperature (thermometer in water)
The engine is overheating. Pull over, switch off and let it cool. Never open a hot coolant cap. Common causes include low coolant, a leak, a failed thermostat or a failed water pump.
Brake warning (! in a circle)
Check the handbrake is fully off first. If it is, the brake fluid may be low or there's a fault in the brake system. Don't drive until it's been checked. See our mobile brake service.
Battery / charging
The car isn't charging properly, often because of the alternator or its drive belt. You're running on battery power alone and may only have a short distance before the car stops.
Airbag / SRS
A fault in the airbag system means the airbags may not deploy in a crash. The car will usually drive normally, but it should be checked promptly. It's also an MOT failure.
Power steering
The steering may suddenly feel very heavy. Drive carefully to a safe place and get it looked at.
Red light on and the car's stuck? We come to you, so there's no need to drive it to a garage.
Call 07831 416334Amber warning lights: get it checked
Engine management (engine outline)
The engine computer has recorded a fault. It could be anything from a loose fuel cap to a sensor, misfire or emissions problem. A diagnostic check reads the fault codes and finds the cause.
ABS
The anti-lock system has a fault. Your normal brakes should still work, but anti-lock won't help in an emergency stop. A faulty wheel-speed sensor is a common cause.
Tyre pressure (! in a tyre shape)
One or more tyres may be under-inflated. Check and adjust the pressures. If the light returns, you may have a slow puncture.
DPF (box with dots)
On diesel cars, the particulate filter is filling with soot. A sustained faster drive can sometimes clear it. If the light stays on, it needs attention before it becomes an expensive repair. See our exhaust and DPF repairs.
Glow plug (coil symbol, diesel)
It's normal for this light to come on briefly before starting. If it flashes while you're driving, the engine has a fault that needs diagnosing.
Traction / stability control
A light that flickers while you're driving on a slippery road is normal: the system is working. If it stays on, there may be a fault, so get it checked.
What if a light is flashing?
A flashing light is usually more urgent than a steady one. A flashing engine management light often means a misfire that can overheat and damage the catalytic converter. Reduce speed, avoid hard acceleration and get it checked as soon as possible.
What to do next
- Note the colour and whether the light is steady or flashing.
- For red lights, stop somewhere safe and switch off.
- Check the basics: oil level, coolant level (when cool) and the handbrake.
- Check your owner's handbook for your exact car's symbols.
- Book a diagnostic check. We read the codes and find the cause at your home or workplace.
Try our interactive warning light checker on the homepage, or get a quote. Diagnostics start from £75, callout included.
Mobile diagnostics across Surrey & West Sussex. The fee is halved if we do the repair.
Book diagnosticsThis guide gives general information only. Warning lights and symbols vary by make and model, so always follow your vehicle handbook. If you're unsure whether your car is safe to drive, don't drive it.