I have been trying to find a method of knowing when my 2.1 Mercedes A Class DPF is regenerating as realise it’s best to let it complete . The only sign I have noticed Is that the idle speed increases to 850 RPM . Normally it sits at 775 RPM when not in regeneration mode . Also I get the tiny rattle sound which I believe happens when in regeneration mode . Anyone else found any method of knowing for sure . I have seen it mentioned that the stop/start does not operate but mine seems too continue working although I do turn it off most of the time manually .