how to fix P0420 code on Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather the necessary tools and parts.
• Ensure the vehicle is parked on a level surface and engage the parking brake.
• Disconnect the negative battery terminal to avoid electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the Sensors:
   • Use an oxygen sensor socket to unscrew the sensors from their locations.
   • Carefully disconnect the electrical connectors.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and ensure they are securely tightened (typically to manufacturer's torque specifications).
   • Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the Exhaust System:
   • Loosen the bolts connecting the exhaust pipe to the catalytic converter using a socket set.
   • Carefully detach the exhaust system to access the catalytic converter.
2. Examine the Catalytic Converter:
   • Check for any signs of physical damage or clogging.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place and secure it with new gaskets and bolts.
   • Tighten to manufacturer's torque specifications to prevent exhaust leaks.

4. Reset the Engine Control Module (ECM)

1. Reconnect the Battery: Reattach the negative battery terminal securely.
2. Erase Trouble Codes: Use the OBD-II scanner to clear the P0420 code from the system.