I am a flight from Charles De Gaulle to Heathrow and each time ATC say my transponder has failed and switch me to VFR. I am starting from the end of the runway with no mods. What is even staranger once ATC has converted me over to VFR then I can request going back to the original flight plan IFR and all is then fine, I even land on AP down the Heathrow 09R ILS!!

Any idea what is happening here.

CJ

Just change your transponder when this happens, bottom right of the throttle.