BentleyPublishers.com_Audi_A6_C5_4.2L_Secondary_Air_Injection_Maintenance.pdf

Audi A6 Sedan 1998-2004, Audi A6 Avant 1999-2004, Audi allroad quattro 2001-2004, Audi S6 Avant 2002-2004, Audi RS6 2003-2004 - 4.2 Liter V8 5V Engine Mechanical, Engine Code(s): BAS

26-50

just

test.

Secondary air

system

The secondary air system is

designed to enable catalytic

converter to heat up and

reach its operating

temperature more quickly

after a cold start.

Principle of operation

Due to extra mixture

enrichment during cold-start

phase, an increased amount

of unburnt hydrocarbons is

carried in exhaust gas. The

secondary air system

improves the afterburning

(oxidation) process in the

catalytic converter, and in this

way reduces toxic emissions.

Heat generated by oxidation

accelerates "light off" of

catalytic converter and

significantly improves

exhaust gas quality during

warm-up.

Advanced

Version: 2.5r01sp0003

Audi A6 Sedan 1998-2004, Audi A6 Avant 1999-2004, Audi allroad quattro 2001-2004, Audi S6 Avant 2002-2004, Audi RS6 2003-2004 - 4.2 Liter V8 5V Engine Mechanical, Engine Code(s): BAS

26-51

Function

After a cold start, engine

control module -3-

activates secondary air

pump -1- via secondary

air pump relay -2-, and

air is fed to combination

valves for secondary air

system -4- and -8-.

At the same time, the

system activates

secondary air inlet valve -

5-, which supplies

vacuum to combination

valves -4- and -8-. The

relevant combination

valve opens a passage

for the secondary air

system to supply air to

exhaust ports in cylinder

head.

Audi A6 Sedan 1998-2004, Audi A6 Avant 1999-2004, Audi allroad quattro 2001-2004, Audi S6 Avant 2002-2004, Audi RS6 2003-2004 - 4.2 Liter V8 5V Engine Mechanical, Engine Code(s): BAS

26-52

1 - Secondary air

injection (AIR) pump

motor -V101-

Location Fig. 2 ,

Page 26-54

Removing and

installing

Page

26-77

2 - Secondary air

injection (AIR) pump

relay -J299-

Location Fig. 3 ,

Page 26-55

3 - Motronic engine

control module

(ECM) -J220-

4 - Right combination

valve for secondary

air system

Location Fig. 4 ,

Page 26-55

Checking

Page

26-79

Audi A6 Sedan 1998-2004, Audi A6 Avant 1999-2004, Audi allroad quattro 2001-2004, Audi S6 Avant 2002-2004, Audi RS6 2003-2004 - 4.2 Liter V8 5V Engine Mechanical, Engine Code(s): BAS

Removing and

installing

Page

26-86

Audi A6 Sedan 1998-2004, Audi A6 Avant 1999-2004, Audi allroad quattro 2001-2004, Audi S6 Avant 2002-2004, Audi RS6 2003-2004 - 4.2 Liter V8 5V Engine Mechanical, Engine Code(s): BAS

26-53

5 - Secondary Air

Injection (AIR)

Solenoid Valve -

N112-

Location Fig. 1 ,

Page 26-54

6 - Non-return valve

Installation position

as shown in

illustration. Arrow

indicates direction