1.1 fiesta cfi keeps failing on co too high anyone helpppppp

hi i have got a fiesta 1.1 lxi i have replaced the cat and lamda sensor with brand new parts but still the co is too high to pass the mot.

here are the readings

co fail 0.76 % 0.30 max

hc pass179 ppm 200 max

lambda pass 0.97 0.97-1.03


second fast idle test

co fail 0.49% 0.50 max
hc pass 179 ppm 200 max
lambda pass 1.02 0.97-1.03

natural idle test

co fail 0.63% 0.50 max

can anyone help me please :banghead:

i have also replaced the cfi unit and still no change with my co reading

thanks for any help given :feedback:

fiesta lxi

have you tried changing the air filter?