Hi , 

First post. I have a 12 plate focus 2litre diesel and every now and again while driving I notice a loud whirring noise like the radiator fan is going flat out and my fuel economy goes down. Even coasting in neutral it reads 42 mpg .

Anyone else come across this problem?

Thanks.

David.

Hi, that'll be a DPF regen.  Totally normal on modern diesels.  

Hi Tom , 

Thanks for that , is that something I have to live with , as it seems to be happening more frequently.

Thanks,

David.

56 minutes ago, David. said:

Hi Tom , 

Thanks for that , is that something I have to live with , as it seems to be happening more frequently.

Thanks,

David.

Yeah, there's not much you can do about it.  It will occur more frequently with age as the DPF slowly fills up with ash, leaving less space for soot.  (Soot is burned during the regen, leaving an ash residue that can't burn or pass through the filter.)  It will also occur more frequently with shorter runs, more cold starts and more stop start driving - which have been unavoidable for many of us during the pandemic.  I'm not even getting 100 miles between regens in my own car currently.