The Impressa F7-F8-F9-F85 Temperature Sensor is secured to the Thermoblock with a T25 Torx screw and the other end attaches to the CPU. The Temperature Sensor measures the temperature of the Thermoblock and transmits the reading to the electronic board to initiate the next step in the process. If the required temperature is not reached, or exceeded, an error code 1-4 may be displayed.