They are easy enough to remove as long as you take care with not straining the wires so best to unplug beforehand to allow the wire to rotate as you unscrew. As far as I know all sensors are a screw fit.
John...when I replaced a sensor on my Sigma I tried a local motor factor who matched up the original for me.....the markings it were barely readable.
Correct and you will need a 22mm spanner or a proper sensor socket.
