Hi all. Just had a run of issues with my 2010 diesel. It has gradually been using more and more fuel and the mpg has dropped down by 7mpg. Eventually found what I hope is the problem. The suction control valve on the fuel pump is prone to failing. It has some plating inside that corrodes and causes over fuelling. It often forces diesel into the sump and thins the oil and kills the engine. If you have noticed a drop in economy check your oil and see if the levels are up. Mine was way high so need to order a new one sensor on Monday. Subaru are aware of the issue but mentioned nothing about it when I spoke to them. They have them on back order with no date for when they will be in at £230!!! I will be getting mine elsewhere. 

Currently having the same issue with drop in mpg about 7-9 mpg on my forester, did you notice a diesle/oil/solvent smell in the cabin at all, only really notice after putting my foot down, will have my mechanic check the sensor