Modern vehicles utilize various technologies to ensure drivers remain as safe as possible behind the wheel. Technology also can alert drivers when their cars are in need of examination, and such is the case when the often dreaded “check engine” light comes on.

While a check engine indicator is seldom good news, it may not mean that expensive repairs are right around the corner. The following are six reasons why check engine lights come on and how to remedy these situations.

1. Faulty/loose gas cap: A faulty gas cap is one of the reasons a check engine light might turn on. A cap that is not tightly closed or one that is poorly sealed enables vapors to escape, which can trigger the light. Opening the gas cap and then resealing it tightly may help; otherwise, a replacement cap may be necessary.

2. Faulty sensor: Sometimes there is nothing wrong with the engine or other components, but the light sensor itself. The check engine light might come on because its sensor is corroded or not working properly.

3. Oxygen sensor failure: The oxygen sensor sends data to the vehicle’s computer, which it uses to create the right mix of air and fuel to enter the engine’s cylinders. The check engine light may come on when the sensor fails or registers a problem with the fuel/air mix.

4. Ignition coils/spark plugs: A check engine light may come on to warn drivers it is time to replace spark plugs and/or ignition coils. According to DigitalTrends, ignition coils generate the electricity needed for spark plugs to ignite the fuel and air mix in the cylinders. Worn coils or fouled plugs can cause any number of issues, including engine misfire.

5. Catalytic converter issues: The catalytic convertor heats up hydrocarbons and other emissions so that they turn into carbon dioxide and water vapor to help protect the environment, offers AutoZone. The converter usually does not fail on its own, but a mechanic can help diagnose what might cause the failure.

6. Electronic powertrain controls: Vehicles are large computerized devices with an array of sensors and modules that run powertrains. Any issues with these sensors, networks or modules can trigger the check engine light.

Depending on the make and model of a vehicle, a check engine light may require less urgency than a flashing light. It always helps to consult with the owner’s manual to help determine issues. Automotive retail stores and mechanics can connect the car’s computer to diagnostic equipment that will issue a diagnostic trouble code (DTC) that can serve as a starting point to address check engine light issues.