Hi all, quick question I have just had my MK4 1.8 (1998) MOT'd and it has failed on Exhaust emission Carbon Monoxide content :- Read 0.51% on first test and 0.59% on second (Max 0.30% pass). Prior to the MOT I did a full service and the MOT garage advised me to use Cataclean. Any other advice would be gratefully received!! Many thanks