Engine noise and particulate filter warning on Audi A6

Start by checking the engine oil level and quality, as low or dirty oil can cause knocking noises and affect engine performance. If the oil is fine, consider inspecting the injectors and fuel filter, as these can also lead to rough running and jerking. For the particulate filter warning, try a longer drive at highway speeds to help regenerate the filter. Let me know how it goes or if you have any further questions!