how to fix P0421 code in Tesla Outback 5th Generation (2015-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical shorts during repairs.
• Allow the engine to cool down completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor (before the catalytic converter).
  • Disconnect the electrical connector and use the O2 sensor socket to unscrew it.
• Install the new oxygen sensor.
  • Apply anti-seize compound to the threads of the new sensor.
  • Torque to manufacturer specifications (typically around 30 lb-ft).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Examine and Replace the Catalytic Converter (if needed)

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if necessary)
• Raise the vehicle and secure it with jack stands.
• Remove the exhaust pipes connected to the catalytic converter.
• Inspect the catalytic converter for physical damage or clogging.
• If replacing, remove the old catalytic converter and install the new unit.
  • Ensure all gaskets are in good condition and replace if necessary.
  • Torque all connections to manufacturer specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the error codes.
• Start the engine and allow it to reach operating temperature.