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Why Is Your Check Engine Light On?

What is the Check Engine Light?

The check engine light (CEL) is an orange, engine-shaped light that illuminates on the driver display when the On-Board Diagnostics (OBD-II) system senses an issue. At best, the check engine light is an inconvenience. At worst, the check engine light is a sign that something is awry in the vehicle’s engine. It’s best to have a reputable auto repair shop take a look at the car to diagnose and fix the problem accurately.

Most Common Causes of the Check Engine Light

A wide variety of engine troubles and issues can illuminate the check engine light, but some problems tend to arise more often than others. Here’s a list of some of the most common problems that trigger the check engine light to come on.

Oxygen Sensor Failure

A faulty oxygen sensor is one of the most common causes of the check engine light coming on in any vehicle. Oxygen sensors measure the amount of oxygen in the exhaust system. The oxygen sensor sends oxygen-level data to the vehicle’s onboard electronics, which uses that information to regulate the mixture of oxygen and fuel that enters the cylinders. A car may not have many other symptoms other than the check engine light if any of the vehicle’s oxygen sensors fail. However, over time, a faulty oxygen sensor can result in damaged spark plugs or catalytic converters. Additionally, faulty oxygen sensors may cause a vehicle to fail an emissions test.

Most newer car models have more than one oxygen sensor. Make sure to have any oxygen sensor issues addressed by a professional to avoid any long-term damage to the vehicle.

Loose Gas Cap

Believe it or not, a loose gas cap is one of the most common reasons for a check engine light to come on in a vehicle. A well-fitting gas cap is crucial to the car’s fuel-delivery system; it keeps gasoline fumes inside of the fuel tank and maintains the correct pressure for the whole system.

If the check engine light turns on right after a fill-up, make sure that the gas cap isn’t loose or improperly sealing. Sometimes tightening the gas cap and letting the car run through a few driving cycles is all that’s needed to reset the check engine light. Even if the gas cap needs to be replaced entirely, most reputable auto repair shops will be able to order the vehicle’s OE (original equipment) gas cap from the manufacturer or a dealer.

Catalytic Converter Failure

Catalytic converters are part of the vehicle’s exhaust system and one of the most common reasons for a check engine light. During an engine’s combustion, carbon monoxide is produced. The catalytic converter turns carbon monoxide into carbon dioxide because carbon monoxide is poisonous, while carbon dioxide is harmless. Regular vehicle maintenance is essential to prevent issues with the catalytic converter. Also, if the vehicle is mostly used to drive short distances, make sure to take it on the highway now and then to ensure the catalytic converter doesn’t get clogged. Make sure to address any issues with the catalytic converter as soon as possible, as it can result in the vehicle failing emissions tests and damage to the vehicle’s exhaust system.

Sparkplug and Ignition Coil Issues

Ignition coils provide the electricity that sparkplugs need to ignite the fuel mixture in the car’s cylinders. Older vehicles often only have one ignition coil, but newer models may use a coil per cylinder. A malfunctioning ignition coil will cause the check engine light to illuminate and can result in multiple different engine issues if not addressed as soon as possible. Spark plugs can also cause trouble, such as engine misfires and hesitation during acceleration. In some cases, the vehicle may shut off entirely due to sparkplug or ignition coil issues. Sparkplug and ignition coils are not usually expensive to replace, and most times, experienced mechanics can replace them in a same-day appointment.

Bad Sparkplug Wires

Another common reason for the check engine light to come on is faulty sparkplug wires. The sparkplug wire transfers electricity from the ignition coil to the spark plug. If the cable is worn or has gone bad, the fuel and air mixture in the engine’s cylinders won’t ignite. If the check engine light is on and the vehicle has a rough idle, lower gas mileage, or a noticeable drop in engine performance, the sparkplug wires may need to be replaced.

Mass Airflow Sensor Failure

The mass airflow sensor (MAF) regulates how much air enters the engine. If the check engine light turns on and the car is also having trouble starting, the mass airflow sensor may need replacing. However, issues with the mass airflow sensor can also mimic other engine troubles. Make sure to have a professional mechanic diagnose and treat the problem as soon as possible to prevent any further engine damage.

Aftermarket Installation Issues

Aftermarket alarms and car stereos may trigger the check engine light due to improper installation. The aftermarket system may drain the battery or prevent the car from starting. If an issue with an aftermarket alarm or stereo system causes the check engine light to illuminate, the system may need to be removed and reinstalled in its entirety by a professional.

Vacuum System Leak

Every vehicle has a vacuum system that is essential to the car’s regular operation. The vacuum system operates the brake booster and also lowers emissions. If the check engine light is on and the vehicle surges during idle, a leak in the vacuum system may be the cause. As the system ages, vacuum hoses and lines can dry out and crack. While the parts aren’t very costly, a vacuum leak can be expensive due to the amount of labor needed to diagnose the issue correctly.

How Can We Help?

Here at Ken Van Damme’s Automotive, we have decades of automotive maintenance and repair experience. If the check engine light on your vehicle comes on, bring it to Ken Van Damme’s Automotive in Portland, Oregon, for comprehensive diagnostic services and repair!

Posted on by Ken-admin
Why Is Your Check Engine Light On?

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