MOT Failure: CO Levels during Fast Idle

[hf turbo]

have you got a cone filter or standard air box? if it's a cone try it with your standard air box

[b-force]

have you got a cone filter or standard air box? if it's a cone try it with your standard air box

Standard air box. The whole car is standard bar the suspension and lack of resonator (not enough room when you have a strut brace on).

With regards to lamda readings; lambda values are given as air:fuel ratio. Therefore if it's above 1 then it must be running lean and below 1 it's rich?

[hf turbo]

not all the time matey, it depends onthe equipment the garage is using sometimes, has the tester tried holding the revs around 5k for 30secs or so then gradually decrease in to the limits?