hello

ive got a fiesta turbo engine etc.. (ofab) in my ka and have got a slight problem with it running lean?
when i took it for mot the guy said it was running very lean and he recommend me to change the Co2 potentiometer as it is reading very low
so i had a new one this week and went back down too have a look and found no change in the readings (0.20 and should be 1.75?)
when the potentiometer is unplugged the reading go up to 2.0 .
has any one come across this or any suggestions?

cheeRS rhys