EML emmisions light

Hi just got a 2004 golf 2.0 gt TDI it's got a full custom system looks like no cat. Just one rear silencer ,it also has something at rear of engine blanked off . I've been driving a bit I've just got emmisions light on stinks on tickover will I need to put an eye on it .its got some like! No idea if mapped any ideas

Could be an EGR block-off. If that's the code that's triggering, may need a tune to eliminate. Surprised the seller didn't say anything, if that is in fact what it is. EGR elimination is considered an upgrade, vehicle inspections aside.