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Took the car for an mot yesterday and the emissions were over 3 times higher than the mot limit . The tester asked me if it had been de catted but it still has the main cats and pre cats . He passed it anyway (thankfully!) as I've used them for quite a few years for mots but this is the first with the rs4. No fault codes showing, car appears to run and fuel economy is ok ( well as good as an rs4 will be haha!). Car has done 121k miles and had a full service including plugs 2k miles ago. Anyone any suggestions what to look at? I've got full edition of Vagcom sonwas thinking of trying log lamda sensor values and mad reading but don't know what they should read if there working fine . Exhaust valves open fine so my thinking was it shouldn't be a vacuum leak somewhere?

they need the cats hot[good wee rev first-idle doesnt help at all] then it falls into place,but i assume your mot man did this as they are pretty savvy and yours sounds "helpful" pre cats might be gutted but you wouldnd tell from looking at them

Mine did the same. Gutted precast. Still got main cats. He let mine go thankfully

Ok thanks for the replies . So nothing to worry about by the sounds of it .

Might need a carbon clean.