Close up of a check engine light on a car dashboard

What causes the check engine light to come on?

While some car owners follow things by the books and get auto maintenance at regular intervals, some fly by the seat of their pants and hope that nothing too bad happens. No matter which camp you are in, the appearance of a check engine light on your dashboard can signal a spiral of negative thoughts. Before you get too worked up, read our top 5 reasons why your check engine light is on below.

Top 5 Reasons Why Your Check Engine Light is On


Loose Gas Cap

A loose gas cap and the escaping fumes that result can signal your check engine light to turn on. Before you head to the dealership, make sure your gas cap is screwed on tightly and wait a few minutes to see if the check engine light will go off on its own.

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Mechanic working on a car engineSpark Plugs

Old spark plugs or fried spark plug wires can also signal your check engine light to turn on. Unfortunately, it’s hard to tell if this is the problem without taking your car in to the dealership. The good news is that if this is the problem it should be a quick and relatively inexpensive fix.


Oxygen Sensor

This one sounds a lot worse than it really is. Replacing an oxygen sensor at the dealership is a relatively minor repair and shouldn’t be too expensive. You don’t want to wait on this repair. A damaged oxygen sensor could be causing your car to chug fuel and waste money.

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Ignition Coil

Another common reason for the check engine light to come on is an old or damaged ignition coil. Like many of the repairs on this list, this one isn’t too bad and shouldn’t cost you more than a few hundred dollars at the dealership. Don’t put off this repair. Waiting could result in more serious damage like a broken catalytic converter.


Catalytic Converter

There is no getting around it. If your catalytic converter is the problem, you will be looking at some costly vehicle repairs that could be into the thousands. However, replacing it is necessary if you want a functioning vehicle.

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