what does it mean if my Toyota Highlander Fourth Generation (2020-present) has a P0420 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety during repairs.
• Raise the vehicle with a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket to unscrew the sensor from the exhaust manifold.
   • Disconnect the electrical connector.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Screw the sensor into place and connect the electrical connector.
   • Torque to the manufacturer's specification (usually around 30-50 Nm).
3. Remove the downstream oxygen sensor:
   • Repeat the same process as above for the downstream sensor.
4. Install the new downstream oxygen sensor:
   • Follow the same procedure used for the upstream sensor.

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

1. Remove the catalytic converter:
   • Unbolt the catalytic converter from the exhaust system using a socket set.
   • Carefully lower the catalytic converter from the vehicle.
2. Inspect the old catalytic converter:
   • Check for signs of damage or clogging.
3. Install the new catalytic converter:
   • Position the new catalytic converter in place.
   • Bolt it securely using the manufacturer's torque specifications.
4. Reconnect exhaust components:
   • Ensure all exhaust components are reattached and secure.

4. Reset the ECU

1. Reconnect the battery:
   • Reconnect the negative terminal and ensure it is tight.
2. Clear the error codes:
   • Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Test drive the vehicle:
   • Drive the vehicle for a short distance to allow the system to recheck the catalytic converter's performance.