Td5 Air flow meter fault

Has anyone else ever had a HIGH current fault with the air flow meter on a 2001 disco td5. The usual fault is LOW current. The local landy enginneering co said they hadn't ever seen this fault befor. I've changed the air floe meter 3 times now and the fault still happens. You can clear the fault and it dosn't come back straight away, but I can't find out what is happening.
Any thoughts or suggestions would be of help:doh:

Is it running OK?

I broke mine cleaning it not so long ago and it did'nt make any difference, have since disconected it all together and she runs fine with out!

Yes it's running ok but not at full proformance as when the ecu sees a fault then it fuels at a flat rate rather than a properly metered one.