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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on the electrical components.
• Allow the engine to cool before starting work.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use an O2 sensor socket to remove the upstream sensor.
3. Install the new oxygen sensor and torque it to the manufacturer's specification (typically around 30 Nm).
4. Repeat the process for the downstream oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust pipes connected to the catalytic converter using a socket set.
2. Remove any heat shields or brackets securing the catalytic converter.
3. Carefully remove the catalytic converter from the vehicle.
4. Install the new catalytic converter, ensuring proper alignment and fitting.
5. Reattach the exhaust pipes and torque them to the manufacturer's specifications.

4. Clear Codes and Test Drive

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code.
3. Start the vehicle and let it warm up to operating temperature.
4. Take the car for a test drive to ensure the check engine light does not reappear.