my Porsche Cayenne E3 (2018-Present) has a check engine light with code P0420

Solution

1. Preparation

• Gather tools and materials.
• Disconnect the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors near the exhaust manifold and catalytic converter.
2. Use a wrench to remove the oxygen sensors from their respective locations.
3. Install new oxygen sensors according to manufacturer specifications and torque them to the recommended values (usually around 30 Nm).
4. Reconnect the electrical connectors to the new oxygen sensors.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. If the catalytic converter is confirmed faulty, support the vehicle on jack stands.
2. Remove the exhaust system components that are obstructing access to the catalytic converter.
3. Unbolt the catalytic converter from the exhaust manifold and the mid-pipe using a socket set.
4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
5. Torque the bolts to the manufacturer’s specifications (consult repair manual for specific torque values).
6. Reinstall any exhaust components removed during the process.

4. Final Assembly

1. Reconnect the battery.
2. Start the engine and allow it to reach operating temperature.
3. Check for any exhaust leaks around the new components.