Hi I am new to this so here goes
My Jetta 2.0TDI has 25K miles and the emission light has just come on what could I check myself I am a trained VW Audi mechanic but that was 25 years ago so need a bit of help here and dont really want the nose bleed related to charges at the local vW shop

any help or pointers would be greatly appreciated

 

check for loose or broken vacume lines
have someone pull the code