how to fix P0420 code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical hazards.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Exhaust gas temperature probe (optional)

2. Replace Faulty Oxygen Sensors

1. Identify the upstream and downstream oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Using a socket wrench, remove the sensors from the exhaust manifold and catalytic converter.
4. Install the new oxygen sensors by threading them into place.
5. Torque the sensors to the manufacturer's specification (typically around 30 Nm).
6. Reconnect the electrical connectors to both sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the exhaust pipe bolts securing the catalytic converter.
2. Disconnect any heat shields or brackets attached to the catalytic converter.
3. Carefully remove the old catalytic converter from the exhaust system.
4. Install the new catalytic converter, ensuring proper alignment with exhaust flanges.
5. Torque the bolts to the manufacturer's specification.
6. Reattach any heat shields or brackets removed earlier.

4. Clear the Codes

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code from the system.
3. Start the engine and allow it to reach operating temperature.