Check engine light on problem

Hi every Daxia,

A quick question on Check Engine Light.

My old Ford Focus (2001) always has a problem of engine light on when it starts. It keeps on when driving, but sometimes it turns off. The scary thing is that all dash meters are off scale when the engine light is off. After while, the engine light is on again, and the functions of all the meters recovers.

Can you please tell what is the problem? Many thanks.