Emmisions failed on M.O.T the high Co2 seems to be the problem. i checked the plugs they are burning normal, changed the air filter,put some redex in the tank and had a blast down the motorway,and it still failed!! the C02 reading has come down to 0.48 from 0.73 on the first fast idle test but on the second one it has shot up to 1.23 whereas it was only 0.45 on the second fast idle test on the first M.O.T. Btw the cat and rear section of exhaust were replaced before last years test .
any ideas greatly appreciated ???
Dave

what car? with what eninge...

Its a Brava 1.2 16v

welll if u dont have error on ecu, it must be (dont think its cat since w/o cat it still shuldnt be that high - depends on the guy that tests it i think) lambda.. since my car 1.6 had 0.3- 0.6 (?) o2 lvl... w/o cat - is registered in that way so i dont need 1.
if lambda would respond correctly it shuld lower it for sure....
works stable?

lambda readings are between .97 and 1.05 reading of .97 passed but 2 readings of 1.03 and 1.05 didnt