Catalytic Converter: Service and Repair

Three-way catalytic converter (TWC), replacing

Special tools:
999 5972 FIXTURE 999 5972 Fixture

Removing the three-way catalytic converter (TWC)

Note! 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.

Preparation




Raise the car.

Remove
- the left front wheel
- the splash guard under the engine
- the rear SIPS member
- the nuts at the joint of the exhaust system downstream of the three-way catalytic converter (TWC)
- the nuts at the joint with the manifold.

Expose the heated oxygen sensor (HO2S) wiring.

Note! Make a note of the routing of the wiring.

Disconnect the connectors for the heated oxygen sensors (HO2S).
Disconnect the brake pipe from its holder on the front SIPS member.

Removing the three-way catalytic converter (TWC)




Position a mobile jack with universal plate 999 5972 FIXTURE 999 5972 Fixture under the catalytic converter.
Remove the screws for the front SIPS member.
Pull back and lower the catalytic converters with their heat deflector plates.

Note! The routing of the heated oxygen sensor (HO2S) wiring over the brake pipe.

Installing the three-way catalytic converter (TWC)

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

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

Transferring components when replacing the three-way catalytic converter (TWC)




Disconnect the wiring holders from the heat deflector plate.
Lift out the heat deflector plate.
Remove the heated oxygen sensors (HO2S).

Note! Mark up the position of the heated oxygen sensors (HO2S) before removal.

Remove the three-way catalytic converter (TWC) mountings. Remove the SIPS member.





Install
- the mountings and SIPS member on the new three-way catalytic converter (TWC)
- the heated oxygen sensors (HO2S) according to earlier markings. Lubricate the thread using paste, P/N: 116 1408. Tighten to 45 Nm.

Note! Handle the new three-way catalytic converter (TWC) boot carefully. It is sensitive to twisting.

Position the heat deflector plate.
Press the rear heated oxygen sensors (HO2S) holders into place.

Installing the catalytic converter unit with the heat deflector plate




Use new nuts and gaskets.

Note! Lubricate all the studs. Use paste, P/N: 116 1408. Avoid skin contact with the paste.

Connect to the manifold. Install all the nuts. Use a mobile jack with universal plate 999 5972 FIXTURE 999 5972 Fixture as support.

Note! Ensure that the heated oxygen sensor (HO2S) wiring is correctly routed over the brake pipe.

Press the brake pipe into place in its holder on the front SIPS member.
Connect to the rear exhaust pipe. Install all nuts loosely.
Install the screws for the front SIPS member.
Remove the mobile jack.

Tighten
- the nuts for the front flange seal
- the front SIPS member
- the rear flange seal nuts.

Install the rear SIPS member. Tighten.

Finishing




Connect the heated oxygen sensor (HO2S) wiring.
Secure the wiring as before.
Install the splashguard under the engine.
Install the left front wheel. See Installing wheels Service and Repair.

Check the function
Test start the engine and check for leakage.