Check engine lights can be a scary sight. You’re driving down the highway and suddenly, your car starts sputtering and seems to lose power.
You know something isn’t right. You can feel it.
You reach down to check the gas cap, maybe your tire pressure is low, or that wacky lawnmower has been polluting the air again…or could it be? The check engine light is on!
Now you have no idea what to do next. If you have ever experienced check engine lights in your car, then chances are you have wondered why it happens and what you should do about them.
There are many reasons these lights come on, but there are also solutions for those who deal with them in their cars more often than not. Read on to learn about the 10 reasons for check engine light, and what to do if that little light icon illuminates on your car dashboard.
What Is a Check Engine Light?
Before digging into the reasons for check engine light, let’s see what a check engine light means. Check engine light is a term used to describe a warning light that appears on the dashboard of certain vehicles.
When this light appears, it usually means there is a problem with the vehicle’s engine or one of its vital components. Depending on the cause of the alert, a check engine light may be difficult to distinguish.
Not all vehicles have check engine lights, but those that do can display one of several different warning icons. The most common is an engine-shaped symbol that may or may not blink on and off. Now, let’s continue to read on for the 10 reasons a check engine light comes on.
1. Oxygen Sensor Failure
If an oxygen sensor is defective, then it can cause a check engine light to turn on.
When this happens, the check engine light will trigger and you will experience a decrease in gas mileage. An oxygen sensor is located on each exhaust port of your car’s engine.
This sensor is responsible for keeping track of how much oxygen is in the exhaust system and sending this information to your computer. If one of these sensors malfunctions, incorrect information about how much oxygen is in your car’s exhaust system will be sent. When this happens, your check engine light will come on and you will experience a decrease in gas mileage.
Other symptoms of a bad oxygen sensor are black smoke coming from the exhaust, hesitation or power surges in the engine, and a foul rotten-egg smell coming from the exhaust.
2. Coils or Spark Plug Problems
When the check engine light comes on, the first thing you should do is get your car inspected by a trusted mechanic. If the problem is as simple as a spark plug that is dirty or needs to be replaced, your check engine light will turn off after a tune-up.
Other symptoms of a coil or spark plug going bad are misfiring of the engine, lack of acceleration, or rough idling.
3. Failure of the Mass Airflow Sensor
The airflow sensor is located on the top of the valve cover and is responsible for monitoring the airflow into the engine. It measures how much air is entering the combustion chamber and compares it to the air currently being used.
If the airflow sensor fails, it will set off the check engine light. This can be caused by a variety of things. A build-up of debris such as leaves or dirt in the sensor can cause it to fail.
If the sensor is damaged and won’t give off accurate readings, the computer will assume that the airflow is too low and set off the check engine light. This can be fixed by cleaning the sensor with a sensor cleaner or by replacing it if the damage is too severe.
Other symptoms of a faulty mass airflow sensor are the engine having difficulty starting or turning over, excessive idling, and jerking during acceleration.
4. Spark Plug Wires Going Bad
The check engine light coming on for spark plug wires going bad is a very common occurrence. Often, the light will come on if the wires on one or both spark plugs have broken or loosened. When this happens, they prevent the spark from getting from the spark plug to the air valve.
This will cause misfires, and the check engine light will come on.
Spark plug wires can become damaged for many reasons. The problem can occur after driving for a long period of time because the heat from the engine can cause the wires to expand and break. Spark plug wires can also become damaged from an accident or from being in the heat of an engine for an extended period of time.
Other symptoms of broken or loosened spark plug wires are the engine misfiring, hesitating, and idling roughly.
5. Fuel Cap Is Loose
Here is another one of those common check engine light causes that you probably haven’t considered before. If your gas cap is faulty or not put on correctly, then it can loosen and become dislodged while you are driving. This can cause a check engine light to display on your car’s dashboard.
To ensure that this doesn’t happen to you, double-check your car’s gas cap to make sure it is tightly secured to your car’s gas tank. If it isn’t, you can use a wrench to tighten it up and prevent a check engine light from coming on.
6. Catalytic Converter Failure
Catalytic converters have been used in most cars since the early 1990s. They are responsible for reducing harmful gases in the exhaust. If it fails, the check engine light will come on.
This could be caused by a number of things. If the exhaust is too highly oxidized, the computer will assume that it is pollution and set off the light. A broken exhaust catalyst will cause your car to lose power, sputter, and fail to reach a steady speed.
This is a serious problem that requires immediate attention. A malfunction with the catalytic converter is one of the most common causes of check engine lights and is a very easy fix.
7. Engine Thermostat Failure
The check engine light could be illuminated because of a failing thermostat. The temperature range for a car’s engine is between 195 and 220 degrees Fahrenheit. As temperature increases, fuel consumption goes up and emissions increase in production.
Coolant from the thermostat controls the temperature. As the ideal temperature is reached, the thermostat opens to allow coolant to flow to the radiator. When the temperature falls below the cozy window, the thermostat closes.
Other symptoms of an engine thermostat failing are weird engine noises, coolant leaking, and high temperature readings.
8. Vacuum Leak
If your check engine light comes on due to a vacuum leak, you’ll want to get this issue looked into right away.
Every vehicle has a variety of functions performed by its vacuum system. The brake booster is vacuum operated, and lowering emissions by routing the fumes through the engine is one of the ways it does so.
If your vehicle’s idle starts surging or settling at an abnormal RPM, a vacuum leak might be the cause. A vacuum leak occurs when a vacuum line cracks or a fitting breaks loose. Cracked fittings and loose connections are common problems.
If you are not doing the job yourself, it can be time-consuming and costly to find the source of a vacuum leak, as it can be difficult to trace.
9. Faulty Fuel Sensor
Another common reason that check engine lights are on is because of a faulty fuel sensor. As with the oxygen sensor, this sensor is located on the exhaust manifold and is responsible for monitoring the amount of gas that is entering the engine.
A faulty fuel sensor will typically cause the check engine light to come on, but it will also cause the car to sputter while driving. If this is happening, then you should look into this issue as soon as possible.
10. An Aftermarket Alarm Problem
If you don’t install an aftermarket alarm system properly, it could drain your battery, trigger the check engine light, or even prevent your vehicle from starting. For example, a leaf from an oak tree might land on the hood of your vehicle during the evening, triggering an aftermarket alarm system that had been installed improperly.
You should get the alarm repaired, reinstalled, or replaced by a technician. The cost of doing it properly is a bit more, but the peace of mind that comes with a good operating alarm is priceless.
Other Possible Reasons For Check Engine Light
When your car reaches a certain mileage, the check engine light may come on. This is common for older cars, but it could also be the result of another issue. It’s important to know the causes so you can fix them quickly and prevent further problems.
Another common reason for check engine lights is if you’re consistently using bad gas or if you’re always running low on gas. If you’re consistently not keeping enough gas in your tank, the pressure will drop in it and everything else in there will start to collapse as well.
This can lead to rusting, coolant build-up, and even oil leaks. While this can happen over time, it’s important to keep an eye on your tank level and make sure that there’s always enough fuel for your car to run properly.
Your check engine light may be blinking on and off when you are driving because the sensor may be receiving false signals. Sometimes the severity of the cause of the check engine light can be based on whether the icon light is blinking or staying illuminated.
Regardless of whether your check engine icon is blinking on and off, it’s best to start a plan of action to fix your car issues.
Don't Ignore Your Check Engine Light
As we’ve discussed, your check engine light could be triggered by a number of different reasons. If you ignore it, you may end up having to deal with more serious car problems down the road.
You don’t want to put your safety or anyone else’s in danger because this small indicating light was ignored.
Your Check Engine Light Is On: Now What?
These reasons for check engine light coming on will give you knowledge of the many causes of this tiny icon appearing on the dashboard of your car. So, now what? What are the next steps to take when faced with this dilemma with your car engine or a component connected to its operation?
You could take care of the basics yourself and attempt to fix the issue. Or you could speak to a mechanic who can fix the issue in hopes of the check engine light disappearing from your car dashboard.
Depending on how serious the problem is, fixing the issue that’s causing your check engine light to come on could get rather expensive. So, is there an alternate solution to the check engine light dilemma?
If none of these solutions work and your check engine light is still on, it’s time to purchase a new vehicle. Your check engine light could be a sign of a very expensive problem, such as your car’s engine components being damaged or a faulty catalytic converter.
Buying a new car will be a very reliable solution, and getting a new vehicle financed is fast with easy approval for all credit types. You can be driving a new and reliable vehicle tomorrow. Apply now to see what you qualify for.