Catalytic Converter: Service and Repair

Three-way catalytic converter (TWC), replacing

Special tools:
999 5543 SOCKET NV-22 HO2S 999 5543 Socket NV-22 HO2S
999 5972 FIXTURE 999 5972 Fixture

Note! As the illustrations in this service information are used for different model years and / or models, some variation may occur. However, the essential information in the illustrations is always correct.

Removing the three-way catalytic converter (TWC)





Remove
- the left front wheel. Applies to B52x4T.
Disconnect the heated oxygen sensor (HO2S) connectors.
Release the heated oxygen sensor (HO2S) wiring from its mountings.

Note! Applies only to B52x4T: Remove the lower rear screw for the heat deflector plate above the turbocharger (TC)

- the nuts for the front exhaust system connection to the turbocharger/manifold
- the SIPS member
- the clamp where the exhaust system divides downstream of the three-way catalytic converter (TWC).
Lift off the exhaust pipe from the turbocharger (TC)/manifold and the rear system.
Lower/draw down the exhaust system.

Hint: Use a mobile jack with universal plate 999 5972 FIXTURE 999 5972 Fixture as support.

Transferring components




Transfer the heated oxygen sensors (HO2S). Lubricate the threads using paste 1161408.

Note! The front and rear heated oxygen sensors (HO2S) are not interchangeable.

Tighten the heated oxygen sensors (HO2S). Tighten to 45 Nm . Use tool 999 5543 SOCKET NV-22 HO2S 999 5543 Socket NV-22 HO2S

Installing the three-way catalytic converter (TWC)

Note! For tightening torques, see: Tightening torque, B5234T9 Tightening Torque.

Note! To ensure that there is no exhaust leakage, see: Flanged joint, assembling Service and Repair.




Lubricate all studs on the turbocharger (TC) using paste, P/N: 11 61 408 .
Lift up the exhaust system and connect it to the rear system.
Then connect to the turbocharger (TC)/manifold.

Hint: Use a mobile jack with universal plate 999 5972 FIXTURE 999 5972 Fixture as support.

Install
- new nuts at the turbocharger/manifold connection.
Tighten to 25 Nm .

Note! Ensure that the flange on the exhaust pipe is flush against the turbocharger (TC).

Note! Applies only to B52x4T: A new screw in the rear mounting for the heat deflector plate.

Secure the heated oxygen sensor (H02S) wiring at the mounting points. Connect the connectors.
- the clamp at the divide downstream of the three-way catalytic converter (TWC).
Use a new clamp and a new screw .
Tighten to 25 Nm
- The SIPS member.
Tighten to 25 Nm
- the left front wheel. See: Installing wheels Removal and Replacement. Applies to B52x4T.

Check
Test drive the engine. Check for any leakage.
Wipe the engine compartment clean.
Ensure that the steering wheel and gear selector lever are clean.