I'm trying to remove the valve cover on my 2001 Focus (1.6, Zetec SE, UK model) to put a new gasket in (oil leak).

In between the connectors for spark plugs 2 and 3 is a cable which passes through a hole in the valve cover and goes to what looks like a yellow plastic connector mounted on the cylinder head - presumably some sort of sensor. The wires connected to the sensor are yellow/red and yellow/green as far as I can tell.

I've no idea how to disconnect the wires, so this is stopping me from removing the valve cover.

Can anyone offer advice how to disconnect these wires?

Cheers