A 3D printer extruder unit for a 3D printer comprising: a printing nozzle configured for receiving a printing material and depositing said printing material, the printing nozzle comprising a nozzle opening, a first temperature sensor arranged at or near the printing nozzle and configured for measuring a first temperature of printing material deposited by the printing nozzle at a first position, a second temperature sensor arranged at or near the printing nozzle and configured for measuring a second temperature of printing material deposited by the printing nozzle at a second position, and wherein the first position is different from the second position, and a processing unit communicatively connected to the first temperature sensor and the second temperature sensor and configured to: - receive a sensor data from the first temperature sensor and the second temperature sensor, wherein the sensor data comprises the first temperature and the second temperature, - compare the sensor data to a predefined threshold data, and - generate, based on the comparison between the sensor data and the predefined threshold data, one or more of an alert and a control instruction for controlling one or more printing parameters of a 3D printer, the 3D printer extruder unit being characterised in that, during a 3D printing process, the first temperature sensor is located in a position downstream of the nozzle opening such as to enable collecting sensor data indicative of a temperature of the latest deposited layer (P3; P2) completed by the 3D printer extruder unit, and the second temperature sensor is located in a position upstream of the nozzle opening such as to enable collecting sensor data indicative of a temperature of a layer (P4; P5) while the layer (P4; P5) is being deposited or already deposited by the 3D printer extruder unit. a printing nozzle configured for receiving a printing material and depositing said printing material, the printing nozzle comprising a nozzle opening, a first temperature sensor arranged at or near the printing nozzle and configured for measuring a first temperature of printing material deposited by the printing nozzle at a first position, a second temperature sensor arranged at or near the printing nozzle and configured for measuring a second temperature of printing material deposited by the printing nozzle at a second position, and wherein the first position is different from the second position, and a processing unit communicatively connected to the first temperature sensor and the second temperature sensor and configured to: - receive a sensor data from the first temperature sensor and the second temperature sensor, wherein the sensor data comprises the first temperature and the second temperature, - compare the sensor data to a predefined threshold data, and - generate, based on the comparison between the sensor data and the predefined threshold data, one or more of an alert and a control instruction for controlling one or more printing parameters of a 3D printer, - receive a sensor data from the first temperature sensor and the second temperature sensor, wherein the sensor data comprises the first temperature and the second temperature, - compare the sensor data to a predefined threshold data, and - generate, based on the comparison between the sensor data and the predefined threshold data, one or more of an alert and a control instruction for controlling one or more printing parameters of a 3D printer, the 3D printer extruder unit being characterised in that, during a 3D printing process, the first temperature sensor is located in a position downstream of the nozzle opening such as to enable collecting sensor data indicative of a temperature of the latest deposited layer (P3; P2) completed by the 3D printer extruder unit, and the second temperature sensor is located in a position upstream of the nozzle opening such as to enable collecting sensor data indicative of a temperature of a layer (P4; P5) while the layer (P4; P5) is being deposited or already deposited by the 3D printer extruder unit.