Q: DPF (Diesel Particulate Filter) melted

Hello. The DPF functions by trapping certain diesel particulates, and periodically goes through a regenerative cycle to burn those particulates (i.e. when you’re on the motorway and get the temperature high enough to regenerate). This is a bit speculative, but perhaps the regenerative phase was not initiated often enough to keep the particulates burned off and too much particulate material accumulated. A regeneration could have occurred that was excessive, creating enough heat to cause the melting you describe. This might occur if you have a high percentage of low-speed or stop and go driving, with few motorway driving segments. I would make sure I was getting regular higher-speed segments of 10 miles/15 kilometers or more on a weekly basis to prevent this accumulation. If you need to have this scoped out by a professional, have a qualified technician inspect the system thoroughly and advise you on the best actions to take at this point.