Skoda octavia miss fire

Hello my beloved octty has started to misfire on one cylinder and I believe its the injector  not 100% sure alot of black smoke coming out the exhaust when reved, was just wondering if anyone can give me guidance on this, do the injectors need coding if I buy another one to replace it? it's a 2007 1.9tdi bxe with 216,000 on the clock many thanks in advance