SundanceUK

Its usually an aftermarket catalytic converter that causes the emissions issue on our cars, OEM ones have a lot more precious metal in them, but the cheaper refits need a really good blow through just before hooking up to the testers sniffer. Don't worry its common and once you know the way around it, most good MOT testers will give you a chance to "warm" the car up a bit before inserting the exhaust tester.

Sundance