My 407 is currently away in the bodyshop after being hit by an idiot though i expect to get it back next week and want to get to the bottom of the regeneration issues. Basically the car is a taxi but i maintain it well and service it every six thousand miles but i have always had regeneration issues with the car ie it runs great for a few days then spends a day constantly trying to regenerate without success so next time i start it up it starts doing a regen again. Sometimes this results in the car going into safe mode and the engine management light comes on. This lasts until i turn the car off and on again then its back in normal mode and the engine management light is off the next day. Now i thought i read that the car may be having trouble regenerating if the glow plugs were past it so is it worth changing them or do you feel the car has other issues?