Why is My Check Engine Light On?

Oxygen Sensor

In your exhaust pipe, there are several small sensors that sample the exhaust from your vehicle to determine the air-to-fuel ratio. This information is transmitted to your vehicle’s computer which then adapts the gas-to-air mixture to ensure that your vehicle’s engine is operating efficiently. When these sensors go bad, it sends a signal to the computer to illuminate the light and make the driver aware that there is a problem. Having good oxygen sensors can improve vehicle fuel efficiency by up to 40%.

Damaged or Loose Gas Cap

Your check engine light may be warning you that there are fuel vapors escaping from the fuel system. When this happens, the EVAP system is not functioning properly, and fuel pressure may also be affected.

Ineffective Spark Plugs

Spark plugs are the small but mighty powerhouses of your vehicle. Their function is to generate a spark inside your vehicle’s internal combustion system. That spark causes the air-to-fuel mixture to ignite to start your engine. These plugs continually generate sparks inside the system to burn fuel as your vehicle needs it so it will continue to run smoothly. Bad spark plug wires can also cause your check engine light to come on.

Battery Issues

Your vehicle’s battery is another important component of engine function. If your battery is weak, faulty, or not fully charged, it becomes ineffective in sending the proper amount of energy to your vehicle’s computer system so your vehicle will function properly. Many vehicles may also have a battery light that may come on with problems involving your battery.

Faulty Mass Airflow Sensor

This sensor measures airflow so your vehicle’s computer can help your vehicle to function properly. When this sensor wears out or otherwise becomes damaged, your vehicle can lose efficiency, stall, or idle roughly. The effectiveness of this component can be related to normal wear and tear or cleanliness. A dirty air filter may cause the sensor to get dirty and trigger the light.

Bad EGR Valve

EGR stands for Exhaust Gas Recirculation. The EGR Valve helps reduce the emission of harmful nitrogen oxides by recirculating metered quantities of exhaust gas into the air intake system. When this valve has a problem, it can result in ineffective power, acceleration, and fuel efficiency.

Catalytic Converter Issue

A catalytic converter is responsible for reducing air pollution, by removing pollutants from your vehicle’s exhaust. It accomplishes this by transforming three harmful compounds: carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful compounds. A sign of issues is a “rotten egg” smell when the light stays on.

Leak in Vacuum

Although not hazardous, it can cause a drop in fuel efficiency and power. Problems with the vacuum system will also trigger your check engine light.