Systems and methods for pressure sensor assembly including improved encapsulation material

A method of encapsulating a sensor unit in a pressure sensor assembly for a compression ignition internal combustion engine, the pressure sensor assembly comprising an external housing unit for the sensor unit, the sensor unit comprising a sensing element defining a pressure-sensing surface, the method comprising;

• providing an air passage for the sensor unit which enables an airflow to be applied to the pressure-sensing surface, in use;
• mounting a mounting surface of the sensor unit on a substrate to leave at least a part of an external surface of the sensor unit exposed including a pressure-sensing surface of a sensing element of the sensor unit;
• providing a filling passage, separate from the air flow passage;
• and
• introducing an encapsulation material through the filling passage so that the encapsulation material surrounds the external surface of the sensor unit which is exposed but excluding the pressure-sensing surface of the sensing element which remains directly exposed to air within an air passage.