Curiously it’s after flashing up another warning “Engine fault, risk of filter clogging” I assumed the dpf was clogged and was pressurising the exhaust, so I went out and bought DPF cleaner unscrewed the 22mm sensor and spayed the cleaner downstream in the exhaust;

And took it for a spin out to kinnegad in 3rd gear hoping it would clear the fault, to no great success. So I went to my new local friendly spanner monkey to run a diagnostic test and it came back saying it needs a DPF eloys fluid top up again. As I only topped it up on January this year I bought the dpf fluid again and topped it up.
75k miles on it now, Malahide housewives are known to do more miles than that. But I think I’ll incorporate cleaning the DPF and checking the Eloys fluid into every service moving forward.