Not sure if it helps Pete, but I remember having a problem with a Fiat Diesel reset the once (Bravo I think).
Ended up going through the other Fiats until it reset (think it was a Grande Punto, but couldn't be sure).

Just a thought, it's not the French 1.6 is it?
If so, depress Accelerator and brake pedals together, turn ignition on and wait for up to 1 minute, or until oil can flashes.