2012 Mondeo 2.0 diesel Euro V model.

I'm getting "P00BD - Mass or Volume Air Flow 'A' Circuit Range/Performance - Air Flow Too High". More specifically, sometimes it's "P00BD:64-AF", sometimes it's "P00BD:64-27" and sometimes it's "P00BD-P".

I've put in a new air mass meter, made no difference. Only seems to occur when the engine has warmed up, it will throw up the "Engine Malfunction" message, sometimes the MIL comes on solid and sometimes not. The car goes into limp mode when it happens.

I've checked the air hoses and can't see any holes or rips. I cannot hear any "whooshing" noises either that some people report.

The car doesn't need to be under particular load when it occurs. I could be cruising along the motorway in 6th gear at 60mph, and it might happen. Equally it has happened moving steadily at 30mph in city traffic. When it does happen, it often goes unnoticed, as in I don't notice any change in engine sound or performance, and the first I know of it is that the engine malfunction message on the dash catches my eye.

Anyone got any words of wisdom before I go stripping the car down?!

Check the air doser (throttle body) as that may be sticking open.