Why does my engine malfunction light come on at random times?

Ford focus 08

Have the computer scanned for free at any auto parts store but don't buy anything, then come back here and ask once you're armed with the code number.

Because you have an intermittent fault somewhere - it will probably get worse.

Have you looked in the owners manual where your Q is answered?

Because it is malfunction

Check to see that your gas cap is sealed! Usually a number one reason for intermittent engine light faults. However, many auto supply stores will be able to connect and read the last fault code and most will even tell you what that code means.

Because you have one of dozens of potential malfunction issues with your Ford. Bring your car to any auto parts store, they will read the code which is causing the light to illuminate. Then you'll know, it's that easy.