There are a number of temperature sensors on the cylinder head, which one did you replace? Usually if you have a electromagnetic fan then there should be a 3 prong temperature switch which activates the electromagnetic fan at 100 deg C, and then at 105 deg C the next switch activates the high speed side of the electric aux fan via a relay (in a compartment situated behind the fuse box). Other models might use a 2 prog temperature switch.