No sure for curtain, but it would make some sense, as pumping loads of diesel into the engine with the aim of making the exhaust gas hotter must surely make the engine hotter too.Latest update is that they think the fan is faulty as the car has started, but never completed a regeneration for quite a few cycles. Anyone experienced this, can confirm or explain further? I know many components get very hot during the regeneration but is the fan linked to a safety cut off I.E in my case the car sees the fan is innop so as a precaution suspends the regeneration as it wont have the correct cooling ?