Top 6 Reasons the Check Engine Light Comes On

Reasons the Check Engine Comes On

It’s happened to all of us. You’re driving along, everything is seemingly normal, and then bam – the check engine light comes on. You don’t see smoke pouring from the hood of your car; there isn’t a noticeable clunking noise. So why did that dang light turn on?

And if we are being honest here, I’m sure that more than a few of us have driven our car for weeks or months (dare I say years?) before taking the car to a service center to investigate the cause of the pesky check engine light.

Knowing the top reasons for the check engine light allows you to take some initial steps before heading to the service department and helps you to evaluate the severity of the issue. Heck, you might even be able to fix the problem yourself!

Instead of assuming everything is fine until your car blows up in a fiery explosion, be aware of these top 6 reasons the check engine light comes on:

 1. Loose Gas Cap

Now wouldn’t you feel silly taking your car in for a checkup, only to find out the check engine light was on because the gas cap was loose? So when that light appears, the first thing you need to do is make sure that the gas cap is on securely and that is it not cracked or damaged.

A cracked or loose fuel cap can cause major issues with your car because fuel vapors are constantly leaking and the gas you paid for is slowing evaporating. Not only that, but you will notice your MPGs dropping as well.

 2. Failing Oxygen Sensor

A malfunction from the oxygen sensor is one of the most common service repairs. So it is safe to say it is one of the most common causes of the doomed check engine light as well.

An oxygen sensor monitors how much fuel is burned and plays a big role in maintaining proper fuel economy. Burning oil and internal leaks can cause an oxygen sensor to malfunction and the check engine light to flip on. Gone unrepaired, a damaged oxygen sensor can substantially decrease your miles per gallon.

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3. Failing Catalytic Converter

Usually a catalytic converter fails because another component of the car fails first, typically an oxygen sensor or spark plugs. The catalytic converter’s main job is to turn carbon monoxide into harmless emissions. When it fails, gas mileage is again affected and after a while, you won’t be able to keep the car running.

The longer you wait to get this fixed, the worse off your car is. So don’t delay if you suspect this to be the issue!

4. Bad Spark Plugs

Spark plugs are crucial in the workings of your engine. Without them, your engine would not be able to combust. When you have a bad spark plug, your engine misfires and often becomes difficult to start. As mentioned before, a failing spark plug can also spell disaster for your catalytic converter, so it’s important to have these up to par.

Replacing a spark plug is pretty easy – you could replace them yourself and have a handy friend or family member do it for you.

 5. Malfunctioning Mass Air Flow Sensor

The mass air flow sensor is responsible for telling the car how much fuel the engine needs based on how much air is coming through the engine. When the air flow sensor is broken, your car’s emissions increase and you guessed it, gas mileage suffers.

It is easy to go months without really noticing any side effects of a bad air flow sensor but after a while, your car will begin to stall frequently.

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 6. Faulty Ignition Coil

The ignition coil transfers power from the generator to the spark plugs. The spark plugs then allow the fuel to ignite and combustion to occur. When the ignition coil is bad, however, your car may backfire, have trouble starting, misfire, or stall. Oh, and did we mention bad fuel economy?

Again, worn ignition coils can also wreak havoc on the catalytic converter so it’s important to make sure these are replaced quickly.

Dick Dyer Toyota’s Service and Parts Departments are here for all of your routine maintenance needs.

About Dick Dyer Toyota

Dick Dyer Toyota,, of the Columbia area carries an extensive inventory of new and used Toyota vehicles, specializing in used trucks. In addition, the South Carolina dealer provides auto service, Toyota parts, and auto financing. Since opening in 1969, Dick Dyer Toyota has upheld the same motto: Your satisfaction is our number one priority!
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