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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor:
  • Use an O2 sensor socket to unscrew the sensor from the exhaust manifold.
  • Install the new sensor and torque to manufacturer specifications (typically around 30 ft-lbs).
• Remove the downstream (post-catalytic) oxygen sensor using the same method.
  • Install the new sensor and torque it to the specified value.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Wrench set, socket set, exhaust hanger removal tool.
• Check for signs of damage or blockage in the catalytic converter.
• If replacement is needed:
  • Loosen and remove the exhaust pipe bolts connecting the catalytic converter to the exhaust system.
  • Use an exhaust hanger removal tool to detach the converter from any hangers.
  • Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  • Tighten all bolts and reattach hangers securely.

4. Clear the Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.