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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative terminal of the battery for safety.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use a socket wrench to remove the oxygen sensors from their respective locations.
   • Tool Required: Oxygen sensor socket
3. Inspect the sensors for signs of damage or contamination.
4. Install new oxygen sensors if necessary, tightening them to the manufacturer's specifications (typically around 30 ft-lbs).
5. Reconnect the oxygen sensor electrical connectors.

3. Inspect and Replace Catalytic Converter

1. If the catalytic converter is confirmed to be faulty, proceed to remove it.
2. Support the exhaust system with a jack or stands to prevent sagging.
3. Detach the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe using a socket set.
   • Tool Required: Socket set, penetrating oil (if bolts are rusted)
4. Remove the catalytic converter from the exhaust system.
5. Install the new catalytic converter, ensuring a proper fit and alignment.
6. Torque the bolts to the manufacturer's specifications (usually around 30-40 ft-lbs).

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.