what does code P0420 mean for my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Apply penetrating oil to the sensor threads and let it sit for a few minutes.
  3. Using the O2 sensor socket, remove the upstream sensor first, followed by the downstream sensor.
  4. Install new oxygen sensors, torque to manufacturer specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger tool.
• Sub-steps:
  1. Remove any heat shields or brackets securing the catalytic converter.
  2. Use the exhaust hanger tool to detach the exhaust pipes connected to the catalytic converter.
  3. Remove any bolts securing the catalytic converter to the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Reattach all exhaust hangers and heat shields, torquing bolts to manufacturer specifications.

4. Clear Error Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the ECU.