With each new model of car, engine diagnostics is getting more sophisticated.  The next generation of autos can detect tire pressure, fluid levels and temperature with alarming accuracy. However, a dashboard display doesn’t have enough bandwidth detail every diagnostic issue. That is why a lot falls to the simple engine light being turned on. When the engine light does come on, it rarely self corrects. Instead, you’ll have to find out what’s wrong on your own or by taking the car into mechanic. Here the four top reasons why your engine light could be on:

A Loose Gas Cap

A loose gas cap is actually one of the most frequent reasons why an engine light flashes on. It is also one of the easiest to fix. If you notice that the engine light has flashed on after you filled up your gas tank, then before you leave the station go tighten up the gas cap.

Bad Oxygen Sensor

Every car has a catalytic converter that cleans your fuel before it is flushed through the exhaust. A bad oxygen sensor could indicate that your catalytic converter is dirty. It could just mean that the sensor has been jammed with fuel and ash molecules. It might also indicate that you have to flush the system. If a bad oxygen sensor is the reason for your engine light being on, then a more detailed computer diagnostic at a mechanic can reveal the specific sensor that needs to be replaced.

Ignition System Failure

Just because your car started doesn’t mean you can’t be dealing with a potential ignition system failure. Another reason for the check engine light coming on is that your spark plugs are faulty. They might need to either be replaced or cleaned.

Dirty Mass Airflow Sensor

The airflow sensor is like the catalytic converter oxygen sensor but instead of being at the end of the car it is for the engine. And engine’s filter doesn’t have a specific sensor. However, the mass airflow sensor which detects how the air moves around the engine can indicate a clog or dirt with that filter. Replacing an air filter is an easy DIY task.

You can probably drive with your engine light on but you shouldn’t go very far before getting it checked by your mechanic.