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

Solution

1. Preparation

• Gather tools and materials needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle using a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the wiring harness from each oxygen sensor.
  3. Use an O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors, tightening them to the manufacturer’s specified torque (typically around 30 Nm).
  5. Reconnect the wiring harness to each sensor.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Sub-steps:
  1. Remove any heat shields covering the catalytic converter if applicable.
  2. Disconnect the exhaust pipes from the catalytic converter, ensuring to remove any bolts or clamps.
  3. Remove the catalytic converter from its mounting points.
  4. Install the new catalytic converter, ensuring proper alignment and fit.
  5. Reattach the exhaust pipes, and secure them with new gaskets and bolts to the manufacturer’s specified torque.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals and ensure they are tight.
• Use the OBD-II scanner to clear the P0420 code and any other related codes from the ECU.