When installing the air line on an Arnott part, it is almost never necessary to remove or tighten the fitting. If removed, Arnott recommends tightening the Voss fitting with maximum 2Nm. When more torque is used, it can damage the screw-thread which will lead to the air spring leaking air on the fitting.
After installation, check if the wiring/connectors are positioned properly. Improper installation or loose connections can generate fault codes.
Arnott delivers its air struts with the proper mounting nuts and bolts. Please use those to facilitate a smooth and easy installation.