Check engine light on: what it means and what to do
The check engine light is the yellow or amber engine-shaped light on your dashboard. It means the car's computer has logged a fault in the engine, exhaust or fuel system. The key question: is it steady or flashing?
Steady or flashing?
- Steady: usually not an emergency. You can keep driving calmly, but get it checked within a few days, not weeks.
- Flashing: usually an engine misfire. Slow down, avoid hard acceleration and heavy loads, and stop at the nearest safe place. Driving on can damage the catalytic converter, which is an expensive part.
- With a red light (oil pressure or temperature): stop safely right away and switch off the engine.
Most common causes
- A loose fuel cap after refuelling. The simplest cause and the first thing to check.
- Oxygen sensor.
- Spark plugs or ignition coils.
- Mass airflow sensor.
- Catalytic converter.
- A leak in the fuel vapour (EVAP) system.
This list is for understanding only. The real cause is only known by reading the fault code.
What to do first
- Note whether the light is steady or flashing, and whether anything changed in how the car drives (shaking, loss of power, a smell, overheating).
- Tighten the fuel cap if you refuelled recently. The light may go off after a few trips.
- Read the fault code with an OBD2 scanner. Codes usually start with a letter and four digits, such as P0420. Many parts shops and garages can read it quickly.
- Don't just clear the code and forget it. Clearing turns the light off but doesn't fix the fault, and it will come back if the problem is still there.
- Ask the garage for a written diagnosis with the code, the cause and the price before any repair.
Can I keep driving or travel with the light on?
If it's steady and the car drives normally, short trips are usually fine with care. For a long trip in the heat, it's better to find the cause first. If it's flashing, don't travel.
Ask Motorak
In the Motorak app you can ask by voice: "My check engine light is on, what should I do?" The assistant answers in Arabic or English, taking your car's details into account. If you've read the code, give it to the assistant and it will explain what it means. After the repair, log the service and its cost in your car's history.
FAQ
The light went off by itself. Is the problem gone?
Not always. The code stays stored for a while, and reading it shows what happened.
Is the check engine light the same as a service reminder?
No. Some cars have a separate service light (a spanner or the word Service). The check engine light means a logged fault.
Does it affect fuel consumption?
It can, especially if the cause is an oxygen sensor or spark plugs.
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About the author
Mohannad Alali
Founder and CEO of Motorak. He writes Motorak's guides on keeping track of a car's maintenance, expenses and documents.
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