I had a look at my TD5 with the Nanocom. A whole load of faults had appeared including ones to do with the EGR and the air conditioning. It no longer has an EGR and I haven't used the air conditioning since last summer. There were slightly more intelligible ones such as 'airflow circuit logged low' and 'high speed crank error'. The faults may relate to an incident a few days ago when I was driving it. The engine hesitated for a few moments and picked up again, but with the engine warning light illuminated. On switching it off and on again I completed the journey with no warning lights. On clearing the faults and starting up again the airflow fault came back and there is a consistently zero reading from the airflow meter. I think the airflow meter may have failed and the other faults generated because the zero airflow signal didn't match the other inputs. Yes, maybe even the aircon fault because there's some discussion online of people experiencing poor acceleration with a failed MAF when the aircon is on.
I think the finger of suspicion is pointing at the MAF, especially seeing as the supply at its multiplug is still live. So I'll try another.