The warning deserves its own brief
Keep the exact message, complete diagnostic report and earlier work. A recurring DPF, EGR or SCR concern should be discussed from that history, rather than being reduced to the name of a guessed part.
State what you want to change
If tuning is also requested, explain normal use and the response you want. Keep that objective separate from the unresolved fault so the proposed work can address the correct question first.
Ask how the scope is agreed
The registration, engine, transmission and existing software help identify the available route. The history helps the workshop explain the checks and vehicle-specific quote. Confirm those details before reserving the visit.
Prepare a Newport enquiry
The diesel warning guide provides a short timeline checklist. Newport, Cwmbran, Caerleon and nearby customers can send the vehicle brief and confirm the Llandow workshop appointment.
Mobile Stage 1 and ECU solutions, or workshop chassis dyno tuning