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

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the pre-catalytic and post-catalytic oxygen sensors.
2. Remove the old sensors: Use an oxygen sensor socket to carefully unscrew the sensors.
3. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them securely. Torque to manufacturer specifications (typically around 30-40 Nm).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust components: Unbolt the exhaust pipe from the catalytic converter using a socket set.
2. Remove the catalytic converter: Detach any heat shields and unbolt the catalytic converter from its mounting.
3. Install the new catalytic converter: Position the new converter and secure it with bolts. Make sure to use new gaskets to prevent leaks.
4. Reassemble exhaust components: Reattach the exhaust pipe and any shields, ensuring all bolts are torqued to manufacturer specifications.

4. Clear Error Codes

1. Reconnect the battery: Attach the negative terminal back to the battery.
2. Use the OBD-II scanner: Clear the P0420 code from the vehicle’s computer.