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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the wiring harness from each sensor.
  3. Use an O2 sensor socket to remove the sensors from the exhaust system.
  4. Install the new sensors and torque them to the manufacturer's specifications (typically 30 Nm).
  5. Reconnect the wiring harnesses.

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

• Sub-steps:
  1. Remove the exhaust heat shield if applicable.
  2. Use a socket set to unbolt the catalytic converter from the exhaust system.
  3. Inspect the old catalytic converter for any signs of clogging or damage.
  4. Install the new catalytic converter, ensuring correct alignment.
  5. Torque the bolts to the manufacturer's specifications (usually around 40 Nm).
  6. Reattach the exhaust heat shield, if removed.

4. Clear Error Codes

• Sub-steps:
  1. Reconnect the battery.
  2. Use an OBD-II scanner to clear the P0420 code from the ECU.
  3. Start the engine and allow it to reach operating temperature.