This is a known problem under Technical Product Information notice number 2028382/5.

This states that the reason moisture gets in there is unfavourable humidity, in other words it's a bad design. The only clue you often get to this is the fault code "P0322 engine speed sensor-no signal" as this is on the same power circuit.

There is no legal or ethical dilemma or question over removing the EGR and or the DPF, IT IS ILLEGAL and in view of the current attitude towards diesel, downright bloody stupid and irresponsible.