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

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the negative battery terminal.

2. Inspect and Replace Oxygen Sensors (if needed)

• Tools Required: O2 sensor socket, ratchet, torque wrench

• Remove the upstream (pre-catalytic converter) O2 sensor:

  1. Locate the upstream O2 sensor near the exhaust manifold.
  2. Use the O2 sensor socket to unscrew and remove the sensor.

• Install the new O2 sensor:

  1. Apply anti-seize compound to the threads of the new sensor.
  2. Torque the sensor to manufacturer specifications (typically around 30 Nm).

• Repeat the process for the downstream (post-catalytic converter) O2 sensor if it is faulty.

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Socket set, torque wrench
• Remove the old catalytic converter:
  1. Loosen and remove the bolts connecting the catalytic converter to the exhaust system.
  2. Carefully detach the catalytic converter from its mounting points.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place.
  2. Secure it with bolts and torque them to specifications (usually around 40 Nm).

4. Reconnect Battery and Clear Codes

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

5. Final Inspection

• Start the engine and allow it to reach operating temperature.
• Check for any exhaust leaks around the new components.
• Ensure all connections are secure.