Engine Warning Lights Explained
Not every warning light means pull over immediately, but some do. Here's a plain-English guide to what's showing up on your dashboard and what to do about it.
Not sure what your light means?
Send us a photo of the dashboard on WhatsApp and we'll tell you what it is and how urgent it is before you even bring the car in.
Send a photo on WhatsAppWhat each light means
Red lights: stop as soon as it is safe
A red light means something is wrong now. Pull over somewhere safe and switch the engine off rather than trying to get home.
Oil pressure warning
What it means. The engine is not getting enough oil pressure. This is the most serious light on the dashboard.
What to do. Stop as soon as it is safe and switch off. Driving on with no oil pressure can destroy an engine within minutes. Do not just top up the oil and carry on, because low pressure and low level are not the same fault.
Engine temperature warning
What it means. The engine is overheating, usually a coolant leak, a failed thermostat or a water pump.
What to do. Pull over, switch off and let it cool. Do not open the expansion tank while it is hot. Continuing to drive risks a warped head or a blown head gasket.
Brake warning light
What it means. Low brake fluid, a fault in the braking system, or simply the handbrake left on.
What to do. Check the handbrake first. If it is off and the light stays on, check the fluid level. If the pedal feels soft or travels further than usual, stop driving and call us.
Battery or charging warning
What it means. The battery is not being charged, normally an alternator or a drive belt problem.
What to do. The car is running on battery alone and will stop when it is flat, usually within twenty to forty minutes. Head straight to a garage rather than parking up somewhere awkward.
Amber lights: book it in, do not ignore it
An amber light means a fault has been logged and needs attention, but it is usually safe to drive carefully to a garage.
Engine management light, also called the check engine light
What it means. The engine control unit has logged a fault code. It covers hundreds of possible faults, from a loose fuel cap to a failing catalytic converter, so the light alone tells you very little.
What to do. Get it scanned. The code narrows it down in minutes. If the light is flashing rather than steady, that usually means a misfire that can damage the catalytic converter, so stop and call us.
DPF or exhaust warning light, diesel only
What it means. The diesel particulate filter is clogging up with soot. Very common on cars used mostly for short stop-start journeys, which describes most driving in East London.
What to do. A steady run at motorway speed for twenty minutes will often clear it. If the light stays on, or a second light joins it, it needs a forced regeneration or a clean before it blocks completely and needs replacing.
Oil level low
What it means. The level has dropped below minimum. Different from the red oil pressure light and much less urgent.
What to do. Check the dipstick when the engine is cold and level, and top up with the correct grade. If it keeps dropping you have a leak or the engine is burning it, and both are worth finding early.
Tyre pressure warning
What it means. One or more tyres has lost pressure, or the system needs resetting after a tyre change.
What to do. Check all four pressures cold against the sticker in the door shut. If one keeps going down you have a slow puncture.
Glow plug light staying on, diesel only
What it means. Normally this light goes out a few seconds after switching on. Staying lit or flashing means a fault in the glow plug or preheat system.
What to do. Get it scanned. It will make the car hard to start in cold weather and can flag an emissions fault.
Safety system lights
The car will drive, but a safety system is not working and that is an MOT failure.
ABS warning light
What it means. The anti-lock braking system has a fault, usually a wheel speed sensor.
What to do. Your brakes still work normally, but they will lock under hard braking. It is an MOT failure, so get it looked at before your test.
Airbag or SRS warning light
What it means. A fault somewhere in the airbag system, often a seat belt pretensioner or a connector under a seat.
What to do. The airbags may not deploy in a crash. It is also an MOT failure. Worth diagnosing properly rather than clearing the code and hoping.
Traction control or ESP light
What it means. Flashing while driving is normal, it means the system is working. Staying on permanently means it has been switched off or has a fault.
What to do. Check you have not pressed the button. If not, it usually shares a sensor with the ABS system and needs scanning.
Is it safe to keep driving?
Amber, car drives normally
Usually fine to drive carefully to book a diagnostic check.
Amber, something feels off
Reduced power or odd noises, book a check in the next day or two.
Red light, any light flashing
Pull over safely and switch off the engine, don't keep driving.
Get your warning light diagnosed
Walk-ins welcome at 430 Burdett Road, Bow, London E3 4JS.