When you see a check engine light on your dashboard, you may be wondering what it means. What does it mean? Why is there a check engine light on my car?

A check engine light is a warning that your vehicle could be in trouble. It’s an indication that there is something wrong with your car’s emissions system. he check engine light will flash or stay on if there’s an issue.

The reason for this light to come on usually has something to do with emissions or safety standards. There are different levels of check engine lights, but they all mean that something is broken and you should get it fixed ASAP!

It can mean everything from a loose gas cap to an engine misfire, so you must know what it means and how to fix it. Here are some most common reasons why your check engine light might be on and what to do about it:

Your engine is misfiring

The most common reason for your check engine light to turn on is that one or more of your spark plugs has become fouled with oil and needs to be replaced. The spark plugs are located in the cylinder head, just above where the air and fuel enter into each cylinder. Each plug has its coil under it, which sends electricity from a computerized control unit (ECU) to ignite the fuel when needed.

Each plug is rated for 100,000 miles before being replaced; if you change them at every tune-up instead of waiting until they’re bad, you’ll save yourself some money on repairs down the road!

Faulty spark plugs or wires

  • Spark plugs and wires are the ignition source for your engine. If they’re faulty, you’ll see a check engine light indicating that there’s a problem with your car.
Spark Plug Electrical Device  - Clker-Free-Vector-Images / Pixabay
Clker-Free-Vector-Images / Pixabay
  • The spark plug is located at the top of each cylinder, while wires connect to each spark plug at one end and run through openings in the head of your engine to reach a distributor on top of it.
  • Over time, both parts can wear out or be damaged by heat, moisture, or other factors that cause them to malfunction.
Engine Engine Block Machine  - ThomasWolter / Pixabay
ThomasWolter / Pixabay

A bad oxygen sensor

One of the most common reasons for the check engine light to come on is a bad oxygen sensor. This sensor monitors the amount of oxygen in your exhaust and sends this information to your car’s computer, which uses it to adjust how much fuel is delivered during acceleration.

A faulty oxygen sensor can cause misfires, meaning your car will run poorly or not at all. While it’s not expensive to replace, it’s also important because it can lead to more serious problems if left unchecked for too long—like burning out another component like your catalytic converter or fuel pump. Misfires are pretty common; about 50 percent of vehicles have them at some point during their lifetime.

Your gas cap is loose or missing

  • A missing gas cap or else the gas cap can be loose.
  • To replace your gas cap, you can go to any car parts store or auto parts website and order one.
  • If you think your fuel tank is leaking, check the condition of your gasoline by placing it in a container filled with water for 24 hours (some states require 96 hours). If the container has any bubbles rising to its surface, then there are air pockets in your fuel tank that need to be removed before filling up again with new gasoline.
  • Check for leaks by spraying soapy water on all hoses and connections leading into and out of the engine compartment; look for bubbles coming from these areas as they indicate leaks in those spots.
  • To test if an old cap has lost its seal: fill up until just under full but leave off overfilling even by an inch; drive around town at least 20 minutes at highway speeds while checking under both sides of the vehicle periodically until coolant levels drop below half-full—you will see bubbles rise as coolant expands due to pressure changes that occur inside the engine when going fast uphill/downhill etc., which means that old cap was not sealed well enough so needs replacing ASAP before damage occurs!

Here are the most common reasons your check engine light is on and what you need to do about it

If it’s still on, there are five common reasons for the check engine light to come on.

  • Fuel cap. If your gas cap isn’t installed properly and is leaking, this could be the culprit.
  • Spark plugs and wires. Check that all of these components are clean and connected properly to prevent an engine misfire or a rough-running vehicle.
  • Oxygen sensor. This sensor checks the amount of oxygen in your exhaust and sends data back to the car’s computer system so that it can adjust fuel use accordingly; if it fails, you may experience decreased performance or even degradation as well as increased emissions from carbon monoxide (CO) into the atmosphere during acceleration or deceleration.


So, now you know the most common reasons for a check engine light. Check out our blog for more fresh content.

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