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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to avoid electrical shorts.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Screwdrivers

2. Inspect and Replace Oxygen Sensors (if needed)

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to unscrew and remove the sensors from the exhaust system.
  4. Install new oxygen sensors, ensuring they are properly torqued to manufacturer specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if needed)

• Sub-steps:
  1. Remove any heat shields or coverings that obstruct access to the catalytic converter.
  2. Detach the exhaust pipes connected to the catalytic converter using a socket set.
  3. Inspect the catalytic converter for physical damage or blockage.
  4. If necessary, remove the catalytic converter by unscrewing the bolts.
  5. Install a new catalytic converter, ensuring it fits properly with gaskets or seals.
  6. Torque the bolts to the manufacturer's specifications (usually around 30-40 ft-lbs).
  7. Replace heat shields or coverings.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear any existing codes from the ECU.
  3. Start the engine and let it idle to ensure proper operation.