Catalytic Converter - Direct Fit

Replace the direct-fit catalytic converters on a 2017 Maserati Levante 3.0L V6 Twin Turbo, including removal of heat shields, oxygen sensors, and exhaust connections.

Warnings

Tools required

Parts

• Catalytic converter (driver side) × 1 — Use OEM or 49-state legal aftermarket
• Catalytic converter (passenger side) × 1 — Use OEM or 49-state legal aftermarket
• Exhaust flange gaskets × 4 — Use OEM specification
• Manifold to catalytic converter gaskets × 2 — Use OEM specification
• Oxygen sensor (if replacing) × 2 — Downstream O2 sensors

Preparation

1. Ensure engine is completely cold to touch (minimum 3 hours after operation)
2. Disconnect negative battery terminal and secure cable away from terminal
3. Raise vehicle on lift or securely support on jack stands at all four corners
4. Spray all exhaust flange bolts, manifold nuts, and oxygen sensor threads with penetrating oil. Allow to soak for 15-30 minutes
5. Locate both catalytic converters behind turbos on left and right exhaust banks
6. Take photos of heat shield positioning and exhaust hanger locations for reference during reassembly

Procedure

1. 1

   Remove heat shields
   Remove the heat shields covering both catalytic converters. Use a 10mm socket to remove the heat shield mounting bolts. There are typically 4-6 bolts per shield. Carefully remove shields and set aside. Inspect shields for damage and replace if cracked or severely corroded.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
2. 2

   Disconnect oxygen sensors (downstream)
   Locate the downstream oxygen sensors positioned after each catalytic converter. Disconnect the electrical connectors by pressing the release tab and pulling straight back. Using a 22mm oxygen sensor socket with wire cutout, carefully loosen and remove both downstream oxygen sensors. Turn counterclockwise steadily without jerking. If sensors are seized, apply additional penetrating oil and allow to soak, then use gentle heat if necessary.
   ⚠Oxygen sensors are expensive and fragile. If reusing sensors, handle carefully and avoid contaminating sensor element with oil or grease.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
3. 3

   Disconnect downstream exhaust connection (passenger side)
   Locate the flange connection between the passenger side catalytic converter outlet and the mid-pipe. Remove the two or three flange bolts using a 13mm or 15mm socket. Support the mid-pipe weight with a jack or wire to prevent strain on downstream hangers. Separate the flange connection and remove the old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
4. 4

   Disconnect downstream exhaust connection (driver side)
   Repeat the process for the driver side catalytic converter outlet connection to the mid-pipe. Remove flange bolts and support mid-pipe as needed. Keep left and right side hardware separated for easier reassembly.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
5. 5

   Remove exhaust hanger support (if equipped)
   Some catalytic converters are supported by rubber exhaust hangers. If present, remove the hanger bolts using a 13mm socket to allow sufficient movement for catalytic converter removal. Use a pry bar to gently separate rubber hangers from mounting points if necessary.
   Torque spec

   Hanger Bolts22 Nm (16 lb-ft)
6. 6

   Disconnect passenger side catalytic converter from turbo
   Locate the upstream flange connection between the passenger side turbo outlet and catalytic converter inlet. Remove the two or three exhaust flange bolts using a 13mm socket. These bolts may be difficult to access due to proximity to chassis and engine components. Use a ratcheting wrench or universal joint socket if needed. Once bolts are removed, carefully lower the catalytic converter and remove from vehicle. Remove and discard old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
7. 7

   Disconnect driver side catalytic converter from turbo
   Repeat the removal process for the driver side catalytic converter. Remove exhaust flange bolts connecting turbo outlet to catalytic converter inlet. Maneuver catalytic converter out from underneath vehicle, being careful not to damage surrounding components or brake lines. Remove and discard old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
8. 8

   Clean all mating surfaces
   Use a wire brush to thoroughly clean all exhaust flange surfaces at turbo outlets, mid-pipe connections, and oxygen sensor bungs. Remove all carbon deposits, old gasket material, and corrosion. Ensure surfaces are flat and smooth for proper sealing. Inspect studs and threads for damage. Replace any damaged studs before proceeding.
   ℹ️Proper cleaning of mating surfaces is critical for preventing exhaust leaks and ensuring correct torque values.
9. 9

   Install new passenger side catalytic converter
   Position new gasket on turbo outlet flange. Apply a thin coat of anti-seize compound to exhaust flange bolt threads. Position new passenger side catalytic converter to align with turbo outlet and mid-pipe connection. Install exhaust flange bolts finger-tight at upstream connection. Support catalytic converter and loosely install downstream flange bolts. Install and reconnect exhaust hanger if equipped.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)

   Hanger Bolts22 Nm (16 lb-ft)
10. 10

    Install new driver side catalytic converter
    Repeat installation process for driver side. Position new gasket on turbo outlet flange with anti-seize on bolt threads. Align catalytic converter with both upstream turbo connection and downstream mid-pipe connection. Install all bolts finger-tight initially. Install and reconnect exhaust hanger if equipped.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)

    Hanger Bolts22 Nm (16 lb-ft)
11. 11

    Torque all exhaust connections to specification
    Starting with upstream connections at turbos, torque exhaust flange bolts to 45 Nm (33 lb-ft) in a cross pattern on passenger side, then driver side. Next, torque downstream flange bolts connecting to mid-pipes to 50 Nm (37 lb-ft) in a cross pattern on both sides. Finally, torque exhaust hanger bolts to 22 Nm (16 lb-ft) if equipped. Verify all connections are properly seated and aligned before final torque.
    ⚠Do not over-torque exhaust fasteners as this can distort flanges and cause leaks. Use calibrated torque wrench.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)

    Hanger Bolts22 Nm (16 lb-ft)
12. 12

    Install oxygen sensors
    Apply a small amount of anti-seize compound to the threads of both downstream oxygen sensors (avoid getting anti-seize on sensor element). Thread sensors into bungs by hand to ensure proper thread engagement. Once hand-tight, use oxygen sensor socket to torque sensors to 45 Nm (33 lb-ft). Reconnect electrical connectors ensuring they click into place securely. Route wiring away from exhaust heat and moving components.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
13. 13

    Reinstall heat shields
    Position heat shields over catalytic converters ensuring proper alignment with mounting holes. Install heat shield bolts and torque to 10 Nm (7 lb-ft). Verify shields do not contact catalytic converters directly and have proper clearance for thermal expansion.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reconnect negative battery terminal and torque to manufacturer specification
2. Lower vehicle from lift or jack stands
3. Double-check that all tools and parts have been removed from under vehicle
4. Verify no loose bolts or disconnected components remain

Verification

• Start engine and allow to idle. Listen carefully for any exhaust leaks at flange connections and oxygen sensor bungs
• Visually inspect all connections for signs of exhaust gas escape (visible smoke or soot)
• Rev engine to 2000-3000 RPM briefly and recheck for leaks under load
• Use OBD-II scanner to verify oxygen sensors are reading properly and no diagnostic trouble codes are present
• Take vehicle for test drive and monitor for any exhaust odors in cabin, unusual sounds, or check engine light illumination
• After test drive, re-inspect all connections while exhaust is hot for any signs of leaks
• Allow engine to cool and re-torque all exhaust flange bolts after first heat cycle (within 100 miles) to ensure proper seal

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