Hi guys and gals

Been a member of the site for quite a while now and have a good gander through regularly, but don't post that much, so hello!!

Anyway, my girlfriend has an N reg 1.1 hcs mk3 fiesta, it has covered 56k miles. It has failed the MOT on emissions as the carbon monoxide (CO) level is twice as high as what it should be!!

The lambda sensor reading on the MOT printout was normal. Does anyone know if there is any sort of adjustment that can be made to lower this CO level? As I understand it the fuel mixture is too rich. If the lambda sensor is giving an ok reading, could it still be that it is knackered, and a replacement would be necessary??

Any help would be much appreciated

cheers

rich