Usually, it is the driver's side mirror on a Volvo S40 that requires replacement due to being hit by passing cars while the S40 sits alongside the road. However, you might find an occasion where you need to install a new passenger side mirror. The passenger side mirror on the Volvo S40 installs just like the driver's side mirror with the absence of one important feature. The passenger side mirror is adjusted manually. Therefore, you do not have to contend with a wiring harness.
Open the Volvo's passenger door and remove the triangular cover that hides the mounting nuts for the mirror. The cover is located inside the door where the mirror attaches to the outside. The cover press-fits into the door frame. Pull on it to remove it.
Hold the mirror in place and remove the three nuts located behind the cover with a long-well socket and ratchet.
Pull the mirror away from the door. The mirror has three threaded bolts inserted into the side that stick through the door. Be careful not to scratch the door with the bolts as you remove the mirror.
Mount the new mirror against the door while seating the bolts through the door into the inside.
Secure the mirror to the door with the three nuts, long-well socket and ratchet.
Press the cover back onto the Volvo's door frame.
