5 Common Reasons Why Your Check Engine Light Is On - Greg's Japanese Auto (2024)

5 Common Reasons Why Your Check Engine Light Is On - Greg's Japanese Auto (1)

Written by WebAdmin on . Posted in Maintenance

It’s one of every car owner’s biggest nightmares– the check engine light has become illuminated in your dash. This is a sure sign of problems under the hood of your car, and it’s hard to know exactly how serious those problems are.

It could be a quick fix, or it could be a problem that leaves you stranded and costs you thousands of dollars unless it’s addressed quickly. Either way, it’s important to get to the bottom of the issue as soon as possible.

Here are 5 of the most common reasons your check engine light might be on.

1. Problem With Your Gas Cap

Of all the reasons your check engine light might be on, this one could be the easiest and least expensive to fix. In some vehicles, the check engine light comes on if the gas cap is missing, loose, or damaged.

Without the gas cap creating an appropriate seal for your fuel system, gas fumes can escape from your vehicle into the atmosphere. This evaporation causes you to lose fuel and have to fill up your vehicle more often.

2. Oxygen Sensor Malfunction

One of the most common reasons your check engine light may come on is that your oxygen sensor is failing. Your local auto repair shop in Western Washington can replace it for you quickly, which will restore your vehicle’s ability to measure unburned oxygen in its exhaust system.

Until you replace this part, your engine will burn more fuel than it really has to, which will reduce the vehicle’s fuel economy. A new oxygen sensor will also help you prevent damage to your catalytic converter and spark plugs.

3. Faulty Spark Plugs

Your spark plugs are responsible for igniting fuel in your vehicle’s combustion chamber. They get their spark from the ignition coil by way of the spark plug wires. A problem with either your spark plug wires or the spark plugs themselves could cause your check engine light to come on.

Ignoring this problem may lead to a clogged catalytic converter, damaged ignition coils, or problems with your oxygen sensor. Healthy spark plugs are also crucial to maintaining your vehicle’s power and fuel economy.

4. Bad Catalytic Converter

The catalytic converter normally fails after other engine problems have been ignored. If yours isn’t working, your vehicle will run hot, waste fuel, and stop performing as well as it used to.

You also need a functioning catalytic converter to pass an emissions test, since it’s responsible for reducing carbon monoxide emissions.

5. Failing Aftermarket Alarm

If you’ve recently had an aftermarket alarm added to your vehicle, that could be the reason your check engine light came on.

A failing product or bad installation can lead to a host of issues including failure to start the engine, a drained battery, and more.

Check Engine Light/ Diagnostics

Here at Greg’s Japanese Auto repair shop, we speak your car’s language and know the ins and outs of your vehicle. We specialize in working with these cars from Japan and Korea because we want to be your best bet for imported car service near Seattle.

We have eight locations all over the Puget Sound Region, ranging from Lynnwood all the way down to Puyallup. On the other side of Lake Washington, you can find us in Bellevue, Renton, and Covington. Come visit any of our auto repair locations in Western Washington, and we’ll help you determine exactly why your check engine light is on.

Image Credit: Shutterstock/Sheila Shelton

5 Common Reasons Why Your Check Engine Light Is On - Greg's Japanese Auto (2024)

FAQs

5 Common Reasons Why Your Check Engine Light Is On - Greg's Japanese Auto? ›

The most common problem is with the oxygen sensor. This sensor assesses how much oxygen remains in your engine after igniting the air-fuel mixture. If these sensors detect a problem with your engine's oxygen use or burn out over time, it will activate the Check Engine light.

What is the most common reason for the check engine light to come on? ›

The most common problem is with the oxygen sensor. This sensor assesses how much oxygen remains in your engine after igniting the air-fuel mixture. If these sensors detect a problem with your engine's oxygen use or burn out over time, it will activate the Check Engine light.

What things make a check engine light come on? ›

The reasons for a check engine light turning on can range from something minor like a loose gas cap to something more serious like a faulty catalytic converter. It could even be a sign of internal engine failure. Ignoring the problem can turn a potentially quick fix into a costly and time-consuming repair.

Can a bad spark plug cause a check engine light? ›

Worn/failed spark plugs, coil packs, or spark plug wires can trigger your check engine light to come on. In today's cars, if a spark plug fails and can no longer ignite the air-fuel mixture, then the most obvious event should be the check engine light coming on or even flashing.

What sensors can cause a check engine light to come on? ›

Five Reasons Why Your Vehicle's Check Engine Light Is On
  • Catalytic Converter. Hopefully, your check engine warning isn't coming on because your catalytic converter is going out. ...
  • Gas Cap. ...
  • Mass Airflow Sensor. ...
  • Oxygen Sensor. ...
  • Spark Plugs.
Feb 3, 2020

What is the first thing to check when the check engine light comes on? ›

Check your gas cap first. Many vehicles have a loose gas cap indicator that will be triggered before your check engine light comes on. If your gas cap is loose or the seal is not tight, the vapor leakage can cause your fuel system to trigger the check engine light.

Why is my check engine light on but my car runs fine? ›

Check engine lights can turn on for a number of reasons. Some can be minor problems such as tightening the gas cap, and others can be serious problems like engine issues. If your vehicle is running fine, the check engine light may signal a minor issue, but it is best to visit a mechanic to make sure.

Can low oil cause a check engine light to come on? ›

Low Oil and Check Engine Light

However, low oil pressure, which can be caused by low oil levels, can be a reason for the check engine light to turn on. Low oil pressure can seriously interfere with your car's performance and disable your vehicle if not addressed immediately.

Can a check engine light be false? ›

It's designed to come on whenever the engine computer detects a problem that could affect the performance of the engine. However, sometimes the check engine light will come on for no apparent reason. This is known as a false alarm.

What are the signs of a bad spark plug? ›

What Are the Symptoms of Bad Spark Plugs?
  • The Car Has Trouble Starting. Image via Flickr by Kevin Reese. ...
  • The Engine Idles. ...
  • The Car Fights to Accelerate. ...
  • The Engine is Very Loud. ...
  • The Engine Misfires. ...
  • The Vehicle gets Poor Fuel Economy. ...
  • The "Check Engine" Light is On.

How long can you drive with a bad spark plug? ›

How long can you drive with bad spark plugs? Ideally, you should replace them immediately.

What is the most common problem when the check engine light comes on? ›

The most likely cause of the check-engine light is a faulty oxygen sensor, which is used to determine the amount of oxygen present in the vehicle's exhaust. While it may cost the motorist a few hundred dollars to repair, ignoring the issue often results in more extensive damages.

Why is my engine light on but nothing seems wrong? ›

Sometimes the light may come on after fueling if the gas cap is a little loose. Or it could mean your catalytic converter needs to be inspected. Either way, it is never a good idea to ignore the problem forever. It could lead to a severe problem by making whatever is wrong with your vehicle even worse.

Will a clogged catalytic converter cause a check engine light? ›

As mentioned, common symptoms of a clogged catalytic converter include an illuminated check engine light, trouble starting the car, poor acceleration, a smell of sulfur or rotten eggs, engine misfires, and poor fuel economy.

Is it okay to drive with the check engine light on? ›

If the light comes on and remains on, yet everything seems to be working like normal, you should be able to continue driving. But it is important to schedule an appointment to have the issue diagnosed and fixed. If the light comes on and it is blinking, this is an indication of something more serious.

How do mechanics see why the check engine light is on? ›

Most auto repair and parts supply chains offer complimentary “check engine” light diagnostic tests. The test is performed using a scanner that reads the diagnostic code stored in the car's computer memory. Each code is associated with a specific issue, whether a failed sensor, a bad spark plug wire or a vacuum leak.

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