Change Pressure Monitor
WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Drain the system, see Draining
Unplug the connector and twist loose the pressure monitor.
Lube the new O-rings with compressor oil.
Tightening torque for pressure monitor: 18 Nm.