Copy the wording accurately
Send the displayed message and any countdown, alongside the registration. Include the date or mileage of fluid top-ups if known. An AdBlue level message and a system fault should not be reduced to the same short description.
List the work already completed
Include previous sensor, wiring or other SCR system reports. Say whether the message cleared, changed or returned afterwards. The history helps establish which earlier findings still need considering.
Agree the current investigation
The workshop discusses the appropriate checks for the exact vehicle. Neither a reset nor a repeated component replacement should be assumed to explain an unresolved warning.
Follow the diesel warning enquiry checklist and send the SCR history before the appointment.
Mobile Stage 1 and ECU solutions, or workshop chassis dyno tuning