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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Elevate the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor by:
  1. Disconnecting the electrical connector.
  2. Using the O2 sensor socket to unscrew the sensor from the exhaust manifold.
  3. Install the new sensor and torque it to the manufacturer’s specifications (usually around 30 ft-lbs).
• Repeat the process for the downstream (post-catalytic) oxygen sensor.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, gasket scraper.
• Remove any heat shields if present.
• Disconnect the exhaust pipes connected to the catalytic converter:
  1. Loosen the bolts and carefully separate the exhaust joints.
  2. Remove the catalytic converter using the socket set.
• Prepare the surface for the new catalytic converter:
  1. Clean the mating surfaces with a gasket scraper to remove old gasket material.
• Install the new catalytic converter:
  1. Position the new catalytic converter and secure it with the bolts.
  2. Torque bolts to manufacturer specifications (typically around 25-30 ft-lbs).
• Reattach any heat shields.

4. Final Checks

• Reconnect the negative battery terminal.
• Clear the P0420 code using an OBD-II scanner.
• Conduct a test drive to ensure proper operation and check for any new codes.