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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove Sensors:
   • Use an oxygen sensor socket and ratchet to unscrew the sensors.
   • Carefully disconnect the electrical connectors.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new oxygen sensors.
   • Screw in the new sensors and connect the electrical connectors.
   • Torque the sensors to manufacturer specifications (usually around 30 Nm).

3. Inspect and Replace Catalytic Converter

1. Access Catalytic Converter: Raise the vehicle using a jack and secure with jack stands.
2. Remove Exhaust Components:
   • Unbolt the exhaust clamps and any hangers securing the catalytic converter.
   • Remove any heat shields if necessary.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it with new gaskets.
   • Torque bolts to the manufacturer’s specifications.
4. Reinstall Exhaust Components: Reattach any removed exhaust parts and ensure all connections are tight.

4. Clear Codes and Test

1. Reconnect Battery: After all repairs, reconnect the battery.
2. Clear Codes: Use an OBD-II scanner to erase the P0420 code.
3. Test Drive: Drive the vehicle for at least 20-30 minutes to allow the engine to enter closed-loop operation and monitor for any recurrence of the code.