Help Finding Fault

[COLZO]

My Gas Monitor Warning Light or EML(?) comes on every now and then so I bought an OBD reader which tells me I have 1 fault but the code comes up as N/A. Has anyone else found this problem and fixed it? The car runs fine and several people have suggested Lambda sensor.

 

[COLZO]

Just to add the car has only done 20k from new and barely goes over 50mph and travels less than 4 miles at a time. Can you clean lambda sensors?

 

[danward]

Mine comes on every other month or so for les than a day then goes off again. I don't worry about it.