Do you have any gas in the system? Re - reading these posts I can't see anywhere that you got it regassed after the pulley was fitted. If it's empty then you'll keep getting 00256 no matter how many sensors you try.
Quote Originally Posted by Bubbauk View Post
I have tried another sensor now which is the exact same from another known working car and I am still getting

00256 - Sensor for refrigerant pressure/temperature Lower limit not reached

Should I try taking it to get re gassed again in case it didn't work properly the first time?