catalytic converter AUDI A4 1999 B5 / 1.G AWM Engine Exhaust System Components Workshop Manual

26-3


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24
9 -
Turbocharger Removing and installing Page 21
-51
10 -
Catalytic converter
Protect from damage by impactRemoving and installing Page 26
-27
11 -
Oxygen sensor - 55 Nm
Upstream of catalytic converterGrease only the threads with high-
temperature lubricant G 052 112 A3. The
lubricant must not get into the slots on the
sensor body. Checking:
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26-4


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24
12 -
Oxygen sensor - 55 Nm Downstream of catalytic converterGrease only the threads with high-
temperature lubricant G 052 112 A3. The
lubricant must not get into the slots on the
sensor body. Checking:
13 -
Gasket
Always replace
14 -
Front exhaust pipe With flexible connection (de coupling
element) Do not bend flexible connection more than
10 - otherwise it can be damaged. Removing and installing Page 26
-32
Align exhaust system so it is free of stress
before tightening clamp Page 26
-34

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26-10


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24
7 -
Gasket Always replace
8 -
Turbocharger Removing and installing Page 21
-51
9 -
Catalytic converter
Protect from damage by impactRemoving and installing Page 26
-27
10 -
Oxygen sensor - 55 Nm
Upstream of catalytic converterGrease only the threads with high-
temperature lubricant G 052 112 A3. The
lubricant must not get into the slots on the
sensor body. Checking:
Pa
ge 10 of 41 Exhaust s
ystem com
ponents, removin
g and installin
g
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yp
e=re
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26-11


Repair Manual, 1.8 Liter 4
-Cyl. 5V Turbo Fuel
Injection & Ignition, Engine Code(s): AWM, Repair Group 24
11 -
Oxygen sensor - 55 Nm Downstream of catalytic converterGrease only the threads with high-
temperature lubricant G 052 112 A3. The
lubricant must not get into the slots on the
sensor body. Checking:
12 -
Gasket
Always replace
13 -
Front exhaust pipe With flexible connection (de coupling
element) Do not bend flexible connection more than
10 - otherwise it can be damaged. Removing and installing Page 26
-32
Align exhaust system so it is free of stress
before tightening clamp Page 26
-37

Pa
ge 11 of 41 Exhaust s
ystem com
ponents, removin
g and installin
g
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26-27

Catalytic converter, removing and
installing


Removing

- Remove heat shield -arrows- above right-hand drive shaft.
- Loosen bolted connection front exhaust pipe/catalytic converter
accessible from below.

Note:
The flexible connection in the front exhaust pipe must not be deflected
more than 10 to avoid damage. - Remove bolt for transmission bracket to exhaust system -arrow-.
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26-28


Note:
Coolant hoses -1- and -3- do not have to be disconnected. - Unbolt coolant expansion tank -2-, -arrows-.
- Disconnect wire to Engine Coolant level (ECL) Warning switch -F66-
and move coolant expansion tank to one side.

- Disconnect wiring connector for oxygen sensors and move wiring
aside.
1 - (brown) to oxygen sensor downstream of catalytic converter -G130-
2 - (black) to oxygen sensor upstream of catalytic converter -G39-
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26-30


- Disconnect wiring connectors as follows:
1 - on ACF valve (in addition, remove ACF valve from air filter housing)
2 - on mass air flow sensor
3 - on Wastegate Bypass Regulator valve -N75-
- Disconnect hose connections, move wiring aside and remove air filter
housing -arrows-.
- Loosen bolted connection of front exhaust pipe/catalytic converter
accessible from above.

- Undo bolts -arrows- of exhaust turbocharger/catalytic converter.
- Remove catalytic converter upward.
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26-31

Installing
Installation is carried out in the reverse order of
removal; note the following:

Note:
Always replace seals, gaskets and self-locking
nuts.

- Grease threads of oxygen sensors with high
temperature lubricant G 052 112 A3. Apply
lubricant only to threads of sensors; the lubricant
must not get into the slots on the sensor body.

- Align exhaust system stress-free Page 26
-34

or Page 26
-37
.

Tightening torques

Components
Nm
Oxygen sensor to catalytic converter 55
Catalytic converter to exhaust turbocharger 30
Front exhaust pipe to catalytic converter 25
Front exhaust pipe to mountings on
transmission 25
Heat shield to transmission 23
Hose clamps for air duct hoses
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26-32

Front exhaust pipe, removing and
installing


Removing

- Loosen bolted connection of front exhaust
pipe/catalytic converter accessible from above.

- Remove heat shield -arrows- above right-hand drive shaft.
- Remove crosspiece for underfloor.

- Unbolt transmission bracket for exhaust system -arrow-.
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26-33

Note:
The flexible connection in the front exhaust pipe
must not be deflected more than 10 or it may
be damaged.

Installing
Installation is carried out in the reverse order of removal; note the
following:
Note:
Always replace seals, gaskets and self-locking nuts.
Tightening torques - Separate exhaust system at clamp -arrows-.
- Loosen bolted connection of front exhaust pipe/catalytic converter
accessible from below.
- Remove front exhaust pipe.
- Align exhaust system stress-free Page 26
-34
or Page 26
-37
.
Components
Nm
Front exhaust pipe to catalytic converter 25
Crosspiece for underbody to body 20
Heat shield to transmission 23
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