how to fix the P0420 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts required.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery negative terminal for safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Use the O2 sensor socket to carefully remove the upstream sensor from the exhaust manifold.
  3. Install the new upstream oxygen sensor and tighten to manufacturer specifications (typically around 30 lb-ft).
  4. Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, jack and jack stands.
• Sub-steps:
  1. Raise the vehicle and securely support it with jack stands.
  2. Inspect the catalytic converter for physical damage or blockages.
  3. If necessary, cut the exhaust pipes as needed to remove the old catalytic converter.
  4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  5. Tighten all connections to manufacturer specifications (usually around 30-50 lb-ft depending on the connection type).

4. Reconnect Battery and Clear Codes

• Tools Required: Torque wrench.
• Sub-steps:
  1. Reconnect the battery negative terminal.
  2. Start the engine and allow it to reach operating temperature.
  3. Use the OBD-II scanner to clear the P0420 code from the engine control module (ECM).