Why Is My Check Engine Light On?

The dreaded check engine light…

When it comes on it’s easy to assume the worst. Thoughts of expensive repairs and the hassle of getting around without your car pop into your head. Is my car damaged? Should I continue to drive it? How do I get it fixed?

There are many potential issues that can cause the light to come on. This means it is  important to get your car looked at by a technician as soon as possible even if it seems to be running normally. Taking care of the issue causing a check engine light quickly can save your car and wallet. A minor issue can cause serious damage if left unaddressed.

At Matson Point S Tire and Auto we can diagnose your check engine light,  address the underlying issue, and get you back on the road.

check-engine-light-on-dash

What is the purpose of a check engine light?

The check engine light is a warning light on your dash that comes on when there is a problem with your vehicle. The light is triggered when your vehicle’s ECU (engine control unit) detects a malfunction within the various systems it oversees. There are a wide variety of reasons why the light can come on. It can be something as simple as a loose gas cap to more serious issues like engine misfires and emissions problems.

How is a check engine light used to find an issue?

In order to determine the exact cause of the problem, the code causing the check engine light needs to be read from the ECU by a technician. Each code corresponds with a specific fault in the system that can be used to determine the exact issue. Based on the code, your technician will be able to tell you the likely reason the light came on.

Read on to learn about some of the most common issues that trigger a check engine light.

Common causes of a check engine light

Remember, there are many different reasons a check engine light can come on. This list contains some of the more common causes.

1. Catalytic converter and oxygen sensors

One common cause of a check engine light can be related to your vehicle’s catalytic converter and oxygen sensors. The catalytic converter is a device in the exhaust which is responsible for reducing the amount of toxic emissions from the engine. When the catalytic converter is not functioning properly (which could be caused by a clog), you can experience a check engine light.

Failed oxygen sensors before and after the catalytic converter can also cause trigger a fault.

dual-catalytic-converters-on-car

Damaged or faulty catalytic converters can cause a check engine light.

2. Fuel cap

A loose, damaged, or missing fuel cap can cause a fault by triggering an evaporative emissions control code. The EVAP system in your car is designed to prevent gasoline fumes from escaping, which are harmful to the environment. If the check engine light comes on in your car, checking the tightness and seal of the gas cap is a quick way to determine if this is the problem.

vehicle-gas-cap-CEL

A loose gas cap can cause a check engine light.

3. Mass airflow sensor

Another potential cause of a check engine light is a faulty or failed mass airflow sensor. The mass airflow sensor monitors the intake of air into the engine, which the ECU uses to determine the correct amount of fuel. When the mass airflow sensor is not functioning correctly, the engine will not run as it should. This can result in the light coming on.

4. Vacuum leak

Your car’s vacuum lines are subject to extreme temperatures and elements, and as a result can crack and dry rot over time. When the vacuum system has a leak, air is entering the system without passing through the mass air flow sensor. This “unmetered air” can cause a host of issues. In addition to a check engine light, you may notice your car idling at a much higher RPM than normal. It may even change frequently between a high and low RPM.

Why is my check engine light blinking?

A blinking check engine light is an indicator an active malfunction which is a much more serious issue that needs to be addressed as soon as possible. If you encounter a blinking check engine light, pull over and do not continue driving until a technician can look at it.

The most common cause of a blinking check engine light is a misfire, which itself can be caused by a variety of issues. Here are some of the most common causes.

1. Spark

The ignition system in your vehicle is responsible for igniting the mixture of gasoline and air in the cylinder. The result is an explosion that drives the piston, propelling your car. The ignition system contains spark plugs, coil packs/distributors and wires that receive electrical current from the alternator and battery. If any of these components fail it can cause a cylinder to misfire.

If left unaddressed, unburned fuel will be deposited in the catalytic converter, resulting in very high temperatures and eventual damage. Replacing a catalytic converter can cost thousands of dollars. To prevent this from happening, pull over immediately if your check engine light begins to blink and call a tow truck.

2. Fueling

Fuel injectors spray a controlled amount of fuel into the combustion chamber of each cylinder. If an injector goes bad or becomes clogged, the cylinder will not get the proper amount of fuel needed. Not only can this condition cause a flashing check engine light, it will result in noticeable rough idling and poor acceleration. Although less common, a faulty or failed fuel pump can cause a similar misfiring issue.

Let us help!

While these are some of the more common causes of a check engine light, there is no way to know for certain without a service technician interpreting the fault codes. Often the code alone does not tell the entire story, and determining the root cause of the problem requires some investigating. Remember, ignoring the light and continuing to drive has the potential to damage your vehicle, leading to much more costly repairs.

Come visit Matson Point S Auto and Tire or schedule an appointment to let us diagnose your check engine light. Our skilled and friendly technicians will ensure your car is running as it should.

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