an emissions warning usually means a problem with the oxygen sensor in the exhaust
to confirm this then by far the best route is to plug in a scan tool and pull off the fault code
as while the o2 sensor is very likely it could also be a problem with the DPF clogging up or a lack of Adblue fluid
so I don't want you to start replacing parts without a fault code to back it up
do you still need help?
Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you