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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Locate the sensor on the exhaust manifold or downpipe.
  2. Use the O2 sensor socket to unscrew the sensor counterclockwise.
  3. Install the new sensor by screwing it in clockwise and torque it to manufacturer specifications (usually around 30 Nm).
• Repeat the process for the downstream (post-catalytic) oxygen sensor if it is found faulty.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the catalytic converter:
  1. Locate the catalytic converter in the exhaust system.
  2. Remove any heat shields or brackets securing it.
  3. Unbolt the catalytic converter from the exhaust pipes using the socket set.
  4. If applicable, use the exhaust hanger removal tool to detach it from the hangers.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place.
  2. Reattach it to the exhaust pipes and tighten the bolts to the manufacturer's torque specifications (usually around 50 Nm).
  3. Reinstall heat shields or brackets as needed.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.