Catalytic converter, removing and installing

WARNING: This page is about a different car, the 2009 Audi A4, 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Removing

Fig 1: Removing Engine Cover

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove engine cover - arrows -.

Fig 2: Removing Coolant Hoses And Unfastening Coolant Expansion Tank

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove coolant expansion tank - arrow - and set it aside with coolant hoses attached.

Fig 3: Identifying Oxygen Sensor Electrical Connectors

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect electrical connector - 1 - for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) G130 and Oxygen Sensor (O2S) Heater 1 (behind Three Way Catalytic Converter (TWC)) Z29 (brown connector) and free up electrical wiring to catalytic converter.
Disconnect electrical connector - 2 - for Heated Oxygen Sensor (HO2S) G39 and Oxygen Sensor (O2S) Heater Z19 (black connector) and free up electrical wiring to catalytic converter.

Fig 4: Identifying Intake, Mass Air Flow (Maf) Sensor G70 Electrical Harness Connector & Air Filter Housing

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect intake hose - 1 - for air filter/turbocharger.
Disconnect electrical harness connector - 2 - at Mass Air Flow (MAF) Sensor G70.
Free up wiring harness on air filter housing and remove air filter housing - 3 -.

NOTE:

Exhaust system decoupling element must not be bent more than 10 ° , otherwise it may be damaged.

Fig 5: Locating Clamping Sleeve

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Loosen clamping sleeve - arrow - and push it rearward.

Fig 6: Separating Front Exhaust Pipe/Catalytic Converter

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Separate front exhaust pipe/catalytic converter - arrows -.
Remove bolt - 1 - at bracket for front exhaust pipe and remove front exhaust pipe.

Fig 7: Removing Nut At Catalytic Converter/Turbocharger From Below

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove nut - arrow - at catalytic converter/turbocharger from below.

Fig 8: Removing Nuts At Catalytic Converter/Turbocharger From Above

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Courtesy of VOLKSWAGEN UNITED STATES, INC.

Remove nuts - arrows - at catalytic converter/turbocharger from above.
Take catalytic converter up and out.

Installing

Installation is in reverse order of removal, note the following:

NOTE:

Replace gaskets and self-locking nuts.

Install exhaust system free of stress → Exhaust system, installing tension free .

Torque specifications

Component		Nm
Catalytic converter to turbocharger		40 ¹⁾²⁾
Mount to subframe		23
Clamping sleeve		23
¹⁾ Replace bolt or nut ²⁾ Coat studs of exhaust manifold and threads of oxygen sensor with hot bolt paste; Hot bolt paste