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5 Reasons Your “Check Engine” Light Comes On

Check Engine

The "Check Engine" light can be one of the most confusing warnings on your dashboard because it offers no explanation as to why it is suddenly necessary to check your engine. It sounds ominous and can be as serious as a malfunctioning catalytic converter or as trivial as a loose gas cap. The main concern when you see the light is to make sure that long-term damage isn't taking place in your engine and that you aren't compromising the safety of your vehicle.

The "Check Engine" light is part of the onboard diagnostics system and it indicates a problem with your emissions system. In most vehicles, the light is yellow and shaped like an engine. A blinking light means the situation is usually serious, such as a severe misfiring of the engine, allowing unburned fuel to dump into the exhaust system, pushing the temperature of your catalytic converter to the breaking point. Slow the car down, find a safe place to stop, and ask a mechanic to run a diagnostic test. A steady light is not an emergency and you can continue driving, but schedule an appointment with your mechanic as soon as possible.

There are five main reasons your "Check Engine" light comes on:

  • Loose or damaged gas cap: The gas cap acts as a seal for the fuel system and helps maintain the pressure in the fuel tank. A loose or damaged cap can reduce gas mileage and increase emissions from your car. A quick tightening of the cap could solve your problem, or it may need to be replaced.
  • Faulty oxygen sensor: An oxygen sensor monitors the exhaust for unburned oxygen. A faulty sensor will not provide the correct data to the onboard computer. It will eventually damage your catalytic converter, which is a costly engine repair.
  • Failing catalytic converter: A catalytic converter helps reduce emissions in the exhaust gases by converting the carbon monoxide and other harmful gases into less harmful emissions. A failing converter can be the result of a faulty oxygen sensor that has not been replaced, negatively affecting your gas mileage and vehicle performance.
  • Faulty mass airflow sensor: This sensor directs the computer in your vehicle to add the correct amount of fuel based on the air that is coming through the engine. When it starts to fail, the car will stall, idle poorly, increase emissions, and decrease gas mileage. An air filter that has never been replaced or improperly installed can sometimes be the culprit. Have your air filter checked and replaced on a yearly basis. While it is possible to drive for months with a malfunctioning mass airflow sensor, it's not a good idea.
  • Bad spark plugs and wires: A spark plug acts as a seal in the combustion chamber and provides the gap for the spark that causes combustion in the engine. Replacing spark plugs is an easy engine repair and in most cases, very affordable.

When the "Check Engine" light illuminates, your car's monitoring system will have "fault codes" that indicate the nature of the problem. Your mechanic can "read" the codes using a scanner, interpret them, and provide a diagnosis.

Remember these five reasons why your "Check Engine" light comes on. Contact our ASE Certified technicians at Kestner Automotive today for more information about engine repair and to schedule an appointment. Our auto shop proudly serves residents in Columbia, SC, and the surrounding area.

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