Flashing light, red light or the car feels wrong? Stop first
If the engine light is flashing, the car is shaking or losing power, or any warning light on the dash turns red, find somewhere safe to pull over and switch the engine off. Don't keep driving to get home. If you're stuck on a busy road, put the hazard lights on, get everyone out on the side away from the traffic if it's safe, and call roadside assistance if you have it. If anyone is hurt or in danger, call 000.
What does the engine light actually mean?
The orange or yellow symbol shaped like an engine is the car's way of saying its computer has seen a reading it doesn't like. That might be an oxygen sensor, the ignition, the fuel mix or the exhaust system. The computer stores a fault code, and the light stays on until the fault is fixed and the code cleared.
A steady light usually means the car is safe to drive gently to a mechanic in the next few days. It doesn't mean ignore it: a small fault left alone can damage something dearer to put right, such as the catalytic converter.
A flashing light usually points to a misfire, where fuel isn't burning properly in one of the cylinders. Unburnt fuel can overheat the exhaust, so treat it as a stop-soon light rather than a book-it-in-next-month light.
What to do in the next ten minutes
Notice how the car feels
Is it running smoothly, or rough, shaking or down on power? A smooth car with a steady light can usually wait for the mechanic. A rough one shouldn't be driven far.
Check the obvious things
Some cars light up after a refuel if the fuel cap isn't clicked shut. Check it once the car is parked. Then look at the rest of the dash: is anything red, or is the temperature gauge climbing?
Take a photo of the dash
A photo of the lights that are on, and a note of when it started (after a refuel, in the rain, on a hill), saves the mechanic time when they call.
Tell us the job
Pick "Engine light on" in the card, add the make and model, and your postcode. The mechanic who takes it will ask what you've noticed and tell you whether it's safe to bring the car in or better to come to you.
Signs it can't wait
- The engine light is flashing rather than steady.
- The temperature gauge is near the top, or there's steam from under the bonnet.
- The oil pressure light, which looks like an oil can, has come on.
- The car has lost power, is shaking, or smells of burning.
- Another light on the dash has turned red.
What the mechanic will do
First they plug a scan tool into the car's diagnostic port, usually under the dashboard on the driver's side, and read the stored codes. A code points to a system, not always to the part, so a good mechanic then tests before replacing anything: a sensor reading, a spark, a vacuum leak.
Ask them to explain which code they found and what they tested to confirm it. You're paying for the finding as much as the part, and a clear answer now saves the light coming back next week.
What you can do, and what's the mechanic's job
You can
- Pull over and switch off if the light flashes or anything turns red.
- Check the fuel cap is on properly once the car is parked.
- Check the oil level on a cold engine, using the dipstick and the owner's manual.
- Note when the light came on and how the car felt.
Leave to the mechanic
- Reading and clearing fault codes, and finding the real cause behind them.
- Anything to do with the ignition, fuel system, sensors or exhaust.
- Deciding whether the car is safe to drive in, or whether a mobile mechanic should come to it.
If it were our car
A steady light and a car that drives normally: we'd send the job today and drive gently until the mechanic has read the code. A flashing light, a rough engine or anything red on the dash: we'd park it somewhere safe and pick "Come to me" or "Won't start or broken down" in the card, rather than risk the drive.