Celsus AIS2251 is an RCA adaptor for compatible Audi four-channel active Bose systems with the red factory audio connector.
A2: 2000–2005
A3: 1996–2013
A4: 1994–2008
A6: 1997–2004
A8: 1994–2002
Allroad: 2000–2005
TT: 1998–2006
The new radio must provide front and rear pre-amplifier outputs. The blue wire connects to its remote output to switch on the factory amplifier. Cable length: 0.15 m. Check the original plugs and Bose system before ordering. Steering-wheel control retention requires a suitable separate interface.