In the know: Common reasons why your ‘check engine’ light is on

Mirage G4

Your vehicle’s instrument panel is littered with various icons that tell the driver relevant driving data. Some are pretty straightforward while others, like the check engine light, might prove to be a little tricky.


  • What are the common causes why the check engine light is on?

    Common causes include a loose fuel cap, a bad spark plug, a faulty spark plug wire, and a malfunctioning oxygen sensor, among others.
  • What's the best fix when your check engine light is on?

    Should replacing any of the common components not fix the issue, it's best to take your car to your trusted mechanic.
  • Today, we break down the common reasons why your car’s check engine light is on.

    1. A loose fuel cap

    One of the most common things that trigger the check engine light is a loose fuel cap. Although it may not look like it, but the fuel cap is a crucial part of your vehicle’s fuel delivery system. Not only does it prevent the fuel from spilling or evaporating but it also allows the fuel system to maintain the correct pressure.

    Your vehicle might detect the altercation in the system, prompting the check engine light to pop up.

    2. Faulty spark plugs

    Bad spark plugs or spark plug wires can also cause the check engine light to come up.

    Your spark plugs are responsible for igniting the compressed air and fuel in your engine and failure in any of the spark plugs in your car’s engine cylinders would signal the vehicle’s system that there’s a problem in the engine.

    The same goes for a faulty spark plug wire as this component transfers electricity from the coil to the spark plug.

    Aside from the signal in your instrument panel, a faulty spark plug or spark plug wire may cause anything from engine misfires or rough idles to the car unexpectedly shutting off.

    3. Bad oxygen sensors

    A malfunctioning oxygen sensor can also trigger the check engine warning. It monitors just exactly how much air enters the engine and measures unburned oxygen in its exhaust system.

    A faulty oxygen sensor may cause your car to use or burn more fuel than necessary, which ultimately affects your ride’s fuel economy.

    4. Catalytic converter failure

    Your catalytic converter converts toxic gases and harmful pollutants from burnt fuel into something less toxic. Running with a broken catalytic converter is not only bad for Mother Earth but it also means you’ll have a hard time passing the emission test. In addition, it will prompt the check engine light to turn on, and resolving this would require the attention of your trusted mechanic.

    Seeing that the check engine light can be caused by a slew of mechanical issues in your vehicle, it’s recommended that you pay your technician a visit. The key is not to panic and carefully go through any possible causes until you reach a pitstop.

    Photo from Mitsubishi

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