Volvo S40

Introduced in the beginning of 2004, the second generation S40 (known as the 2004.5 Volvo S40) introduced a new design based on the Volvo P1 platform built at the Volvo Cars factory in Ghent, Belgium. At the same time, the V40 was replaced by the estate V50, also based on the P1 platform and built in Ghent.

Information provided by: https://en.wikipedia.org/wiki/Volvo_S40#Second_generation_(2004%E2%80%932012)

Wiring Information
PLEASE NOTE: Failure to disconnect battery prior to removal of factory headunit may result in an engine warning light being displayed. This would need to be cleared by a Volvo repair agent with the proper scan tool.