DPF has been illegal for years but very hard to enforce with a visual inspection as the canister is still in place. The sensors are actually switched off by the remap so that Regen is not triggered. Regen happens at 800° which if a lot of short stop start journeys are made this never happens hence the clog up. BG44 or Archoil coats the soot build up and lowers the burn temperature to 400° making Regen much more effective. It also cleans the whole fuel system like injectors, EGR, combustion chambers etc. If the DPF is really that clogged then a professional clean can be done by someone like The DPF Doctor network who will scan for underlying issues first because there's normally something else causes the DPF not to work properly, fix that and then clean the system. My car is an early 2006 DPF fitted golf with 56000 miles. I've put a bottle of BG44 in regularly and everything is fine. Very few DPFs 'fail' there is normally something else causing it but a lot of garages don't understand DPFs and the easy fix is take it off but this is illegal and as I said, the mot is changing from visual inspection to a proper emissions test soon. You have to think also about your insurance as DPF removal is an instant mot failure if detected so your insurance will be invalid as your driving an unroadworthy vehicle.
