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

Solution

1. Preparation

• Gather tools and materials: OBD-II scanner, multimeter, socket set, jack and jack stands, safety goggles, gloves, and oxygen sensor socket.
• Ensure the vehicle is parked on a level surface and the engine is off and cool.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Disconnect battery: Disconnect the negative terminal of the battery to prevent any electrical shorts.
3. Remove the oxygen sensors: Use an oxygen sensor socket to carefully unscrew the sensors from the exhaust system.
4. Inspect the connectors: Check the wiring and connectors for any signs of wear or corrosion. Replace if necessary.
5. Install new sensors: Apply anti-seize compound on the threads of the new sensors and install them in their respective positions. Torque to manufacturer's specifications (typically around 30 Nm).
6. Reconnect the battery: Reconnect the negative battery terminal.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Lift the vehicle: Use a jack and jack stands to safely elevate the car.
2. Remove the exhaust components: Depending on the design, you may need to remove bolts and hangers securing the exhaust system to access the catalytic converter.
3. Inspect the catalytic converter: Check for any physical damage, such as dents or rust.
4. Replace if necessary: If the catalytic converter is found to be faulty, remove it and install a new one, ensuring all gaskets and seals are replaced. Torque the bolts to manufacturer's specifications.
5. Reassemble exhaust system: Reattach any components removed, ensuring all connections are secure.