how to fix P0420 code on my Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery (negative terminal) to ensure safety during repairs.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove Oxygen Sensors: Use an oxygen sensor socket to unscrew and remove the sensors.
3. Install New Oxygen Sensors: Apply anti-seize compound to the threads of the new sensors. Install them, tightening to the manufacturer's specification (usually 30-40 Nm).
4. Reconnect the Electrical Connectors: Ensure all connectors are secure.

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

1. Remove Exhaust Components: Unbolt the exhaust components leading to the catalytic converter using a socket set. Carefully lower the exhaust system.
2. Remove the Catalytic Converter: Unbolt the catalytic converter from the exhaust pipes and any mounting brackets.
3. Install the New Catalytic Converter: Position the new catalytic converter and torque the bolts to the manufacturer's specifications (usually around 34-40 Nm).
4. Reassemble Exhaust Components: Reattach any previously removed exhaust components.

4. Clear Codes and Test

1. Reconnect the Battery: Reattach the negative battery terminal.
2. Use OBD-II Scanner: Clear the P0420 code using the OBD-II scanner.
3. Test Drive: Drive the vehicle for a short period (typically 20-30 minutes) to monitor for any reoccurrence of the code.