Why your Check Engine Light is On: 5 Causes to Explore

May 13th, 2015 by

No driver wants to see that the check engine light is on in their vehicle. The reason the check engine light is on can range from something as easy to fix as tightening your gas cap to being as troublesome as needing a new catalytic converter. However, in some cases drivers mistake the check engine light for the service required light. The check engine light is typically orange, yellow, or amber, however it differs between manufacturers. Here are five reasons why your check engine light is on.
check engine light is on

Why your Check Engine Light is On

  • A loose gas cap Many websites, like Edmunds, suggest checking to see if the gas cap is on tight enough. Tightening might solve the problem, but in some cases “it will take the light a little while to shut off,” according to Edmunds.
  • The oxygen sensor needs to be replaced This sensor measures the amount of oxygen that is in the vehicle’s exhaust system. Not fixing the sensor could mean “as much as a 40 percent drop in fuel economy,” according to Bankrate. The drop in fuel economy is due to the engine burning more fuel than needed, according to AutoZone. The website further states that a faulty sensor can damage the vehicle’s spark plugs and catalytic converter.
  • Failing catalytic converter According to Bankrate, a catalytic converter usually doesn’t fail unless there is another issue, which AutoZone lists as a faulty oxygen sensor, defective mass airflow sensor, or spark plugs or plug wires that need to be replaced. The catalytic converter converts carbon monoxide into carbon dioxide.
  • Mass airflow sensor needs to be replaced If this sensor is not replaced you may experience a drop in performance and fuel economy, according to AutoZone. It is the job of the mass airflow sensor to determine how much fuel needs to be used based on the amount of air in the engine. If this sensor is faulty it could also damage the spark plugs, catalytic converter, or oxygen sensor.
  • Defective spark plugs Failing spark plugs can damage the catalytic converter, says Bankrate. Spark plugs “ignite the air/fuel mixture in the combustion chamber,” according to AutoZone, and if the spark plugs or wires need to be replaced you may experience a reduction in power. If the spark plugs need to be replaced, the ignition coils might need to be checked as well.

Edmunds also points out that the check engine light can come on when there is a change in humidity, but that “the light should go off by itself after a short time.”
Call Fisher Auto in Boulder, Colo., at 303-245-6414 to schedule an appointment to find out why your check engine light is on. It’s important to diagnose and repair the problem early on so one problem doesn’t potentially evolve into several others.