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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety during the repair.

2. Inspect and Replace Oxygen Sensors

1. Locate the sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect the sensors: Unplug the electrical connectors from both oxygen sensors.
3. Remove the sensors: Using an oxygen sensor socket, carefully unscrew both sensors from their mounting locations.
4. Install new sensors: Apply anti-seize compound to the threads of the new sensors and install them in the same locations, tightening to manufacturer's torque specifications (typically around 30 lb-ft).
5. Reconnect the sensors: Plug the electrical connectors back into the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check for physical damage: Examine the catalytic converter for dents, rust, or any structural issues.
2. Remove exhaust components: Unbolt the exhaust pipe from the catalytic converter using a socket set, and remove any hangers that may be obstructing access.
3. Remove the catalytic converter: Unscrew the bolts holding the converter in place; replace any gaskets if damaged.
4. Install the new catalytic converter: Position the new converter and secure it with bolts, ensuring to replace any exhaust gaskets.
5. Reassemble exhaust components: Reattach the exhaust pipe and hangers, making sure everything is aligned correctly.

4. Clear Error Codes

1. Reconnect the battery: Once repairs are completed, reconnect the negative battery terminal.
2. Use the OBD-II scanner: Clear the P0420 code and any other related codes from the vehicle's computer.