how to fix P0420 code on BMW 5 Series F10/F11 (2010-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the exhaust system to cool down before starting work.

2. Replace Faulty Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet set, torque wrench.
• Remove the oxygen sensor located before the catalytic converter by using the O2 sensor socket.
• Install the new oxygen sensor, ensuring it is tightened to the manufacturer's specified torque (usually around 30 Nm).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter or saw, gasket scraper, high-temperature exhaust sealant.
• Raise the vehicle using a jack and secure it with jack stands.
• Disconnect the exhaust pipes from the catalytic converter using the socket set and exhaust cutter if required.
• Remove the catalytic converter from the vehicle.
• Clean the exhaust flanges with a gasket scraper to ensure a proper seal when installing the new converter.
• Install the new catalytic converter and reconnect the exhaust pipes, ensuring all connections are secure and leak-free.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's memory.
• Start the engine and allow it to idle for a few minutes to check for leaks and proper operation.