[mral1515]

That wont do you any good. The heater side of the sensor is bad. This means the heating element in sensor is either shorted out or has an open circuit. The sensor should have 4 wires. 2 are for the reading of oxygen content and the other 2 are for the heater unfortunatly this heater gets very hot very fast so it can put your vehicle in closed loop operation as soon as possible. After doing this over and over they will go bad.

As far as cleaning your mass air flow sensor. You can do that any time you want. They get dirt and grime on them and are unable to read the correct amout of air coming through the intake.

I don't remember where the efi fuse without looking at an Echo I couldn't tell you. It is either in the fuse box under the hood by the battery, or in the fuse box under the dash.