It's never good to ignore any dashboard warning lights on your car, as these lights are triggered by sensors in the car that alert you to problems that might otherwise be easy to overlook. Ignoring these lights can mean running low on oxygen or suffering an electrical shutdown or other very damaging problem. If that "check engine" light does come on, note a few things that could be causing it so you know what tests to have done and what to expect by way of repair bills:
1. A dying battery
You would think the battery light on the dashboard would come on when the car's battery is dying, but this isn't always the case. The check engine light may come on when it senses that electrical systems in the car are not getting enough power, or that the car struggles to start. The battery light on the dashboard may come on when there is a problem with the alternator, but not necessarily when the battery is low; if you notice dimmed headlights or other signs of electrical problems, have the battery tested before anything else.
2. An oxygen sensor or bad boot
Your car needs oxygen in the engine to create combustion, and a sensor notes how much oxygen is needed to start the car and keep it running. The oxygen boot is a long, rubber piece that delivers this oxygen to the engine. When that sensor or boot starts to fail, the car may struggle to run and you may notice a rough idle, or that it grinds before starting. The check engine light will also usually go on when the sensor begins to break down or there isn't enough consistent oxygen getting to the engine, such as when it's leaking out through cracks in that boot.
3. Bad fuel pump or injectors
As with an oxygen sensor, you need a steady and consistent amount of fuel in order to maintain combustion in the engine even when idling or in park. When the car senses that the fuel pump or the injectors are failing, that sensor may trigger the check engine light, even though there is fuel in the car's tank. Note if you need to rev the engine to keep it idling or give it lots of gas when you start it, as this often means that the car is not getting adequate fuel and the pump or injectors should be checked.
Have more questions? Try contacting a motor mechanics expert for more information and help.