how to address P0420 code on my BMW 5 Series G30/G31 (2017-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.
• Allow the exhaust system to cool down before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor (pre-catalytic converter) using the O2 sensor socket.
• Inspect the sensor for carbon buildup or damage.
• If faulty, install a new oxygen sensor and torque it to manufacturer specifications (usually around 30 Nm).
• Repeat for the downstream oxygen sensor (post-catalytic converter) if needed.

3. Examine the Catalytic Converter

• Tools Required: Jack and jack stands, exhaust pipe cutter (if necessary)
• Raise the vehicle safely using jack stands.
• Inspect the catalytic converter for any signs of damage, such as dents or cracks.
• If the converter is damaged or clogged, remove it by disconnecting the exhaust pipes and any mounting brackets.
• Install a new catalytic converter, ensuring proper alignment and sealing with gaskets.

4. Clear Codes and Reconnect Battery

• Reconnect the battery negative terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.
• Ensure all connections are secure and there are no exhaust leaks.