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.

Preparation




Remove the splash guard from under the engine.

Remove:
- the connectors for the heated oxygen sensors (HO2S)
- the wiring for the heated oxygen sensors (HO2S) from the mountings
- the screw for the mounting for the engine stabilizer brace on the engine
- the engine stabilizer brace between the suspension turrets
- the plastic charge air pipe. Place to one side
- the plastic intake pipe. Put it to one side.

Removing components





Remove:
- the intake and charge air pipes from turbocharger (TC)
- the heat deflector plates
- the upper heated oxygen sensors (HO2S)
- the expansion tank cap.

Removing three-way catalytic converters (TWC) / front exhaust pipe





Remove:
- the nuts. Disconnect the front exhaust pipe from the turbocharger (TC)
- the nuts where the exhaust pipe divides downstream of the three-way catalytic converter (TWC)
- the center SIPS member.
Disconnect the brake pipe from the clips on the front SIPS member.
Remove the screws from the front SIPS member.
Slide the three-way catalytic converter (TWC) (with the heat deflector plate) back and then lower it.

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





Transfer:
- the SIPS member with the exhaust system mountings
- heated oxygen sensors (HO2S).
Lubricate the heated oxygen sensors (HO2S). Tighten the heated oxygen sensors (HO2S). See: Tightening torque Tightening Torque. Use tool 999 5543 SOCKET NV-22 HO2S 999 5543 Socket NV-22 HO2S.

Installing three-way catalytic converters (TWC) / front exhaust pipe





Warning! Avoid skin contact with copper paste.

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

Lubricate the studs on the turbocharger (TC). Use copper paste 116 1408.
Lift up the exhaust system and connect it to the pipe flange. Use a new gasket and new nuts. Do not tighten.
Then connect the exhaust system to the turbocharger (TC).





Install:
- new nuts at the connection to the turbocharger (TC)
- the front SIPS member. Do not tighten
- the brake pipe in holders on the SIPS member.
Tighten the exhaust pipe at the turbocharger (TC). Tighten to 25 Nm.

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

Tighten the exhaust pipe where it separates downstream of the three-way catalytic converter (TWC). Tighten to 25 Nm.
Install the rear SIPS member. Tighten to 25 Nm.
Tighten the front SIPS member. Tighten to 25 Nm.
Connect the connector for the rear heated oxygen sensors (HO2S) and clamp the wiring.

Installing components





Install:
- the upper heated oxygen sensors (HO2S). See: Tightening torque Tightening Torque
- the heat deflector plates
- the intake and charge air pipes from the turbocharger (TC)
- the plastic intake pipe
- the plastic charge air pipe
- the engine stabilizer brace between the suspension turrets.
Connect the connector for the front heated oxygen sensors (HO2S) and clamp the wiring.

Finishing
Test drive the engine.
Check for leakage.
Install the splashguard under the engine.