But the code must only have afew diffrent digits for sat nav. They muat be no nav, low line, high and jap.
Mine had it from factory and when I had it on T4
I deselected the high line and set it to no nav and also removed single point entry. New code applie and battery reset and then it was re applied and made no diffrence.
So I dont think its down to T4
I suspect my MK 3 is an early one dated Nov 2001 and I suspect its had no updates since.
I know there is afew updates for the Rover units but nobody seems to have the discs.