To unplug, I used along screwdriver. You can see the "locking" mechanism and there is a slot there. Put the blade of the screwdriver in that slot, twist it a little and push up on the screwdriver, while pulling down on the sensor wire. I would only pull on the wire if you are defiantly replacing the sensor. Otherwise you should pull on the plug while screwdriver is in the slot, so you don't risk damaging the wires going into the plug.