While your car can’t talk, it communicates with you using chimes, icons, and messages. One icon that you should never ignore is the orange, engine-shaped one that is usually found in the instrument cluster. It turns on when the car’s onboard computer detects a problem.

Don’t panic if you see it — it doesn’t necessarily mean you’ll need to give your next paycheck to the nearest mechanic. Problems that trigger a check engine light are sometimes basic and quick to fix. Don’t ignore it, either, and get it checked out as quickly as possible.

Here are the 10 most common problems that can trigger a check engine light. Keep in mind that the fault code that caused the light to turn on in the first place is stored in your car’s onboard computer, and you can retrieve it using a simple device to get a precise idea of what exactly is wrong under the hood. Doing this on your own will save you money in the long run.

Oxygen sensor failure

The oxygen sensor (sometimes called an O2 sensor) measures the amount of unburnt oxygen in a car’s exhaust system. It sends data to the vehicle’s computer, which uses it to regulate the mixture of air and fuel that enters the cylinders. An engine will keep running even if an O2 sensor needs to be replaced, but it will burn more fuel than usual. In the long run, a bad O2 sensor can damage components like spark plugs and the catalytic converter. It may also cause a car to fail an emissions test.

On average, a quality O2 sensor will set you back about $175, but the cost of labor will vary greatly depending on the vehicle’s make and model, as well as your geographical location. Finally, keep in mind that most late-model cars have more than one O2 sensor.

Loose fuel cap

A loose fuel cap is one of the most common reasons why the check engine light turns on. The cap is a crucial part of a car’s fuel delivery system. It notably prevents gasoline fumes from leaving the fuel tank, and it helps keep the whole system under the correct pressure.

If your check engine light turns on immediately after a fill-up, pull over and make sure the cap isn’t loose — or still on your car’s roof. Sometimes the cap needs to be replaced, but it’s not a problem that’s going to hit your wallet hard. Most auto parts stores carry universal-fit gas caps that cost somewhere in the vicinity of $15.