how to fix P0420 code in Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, and safety glasses.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
2. Disconnect Electrical Connectors: Carefully disconnect the electrical connectors from both sensors.
3. Remove Sensors:
   • Use the appropriate socket to unscrew the sensors from the exhaust manifold and catalytic converter.
4. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Screw in the new sensors and tighten to manufacturer's specifications (typically 30 Nm or 22 lb-ft).
5. Reconnect Electrical Connectors: Reattach the O2 sensor connectors ensuring a secure fit.

3. Inspect and Replace the Catalytic Converter

1. Examine the Catalytic Converter: Check for physical damage, rattling, or signs of blockage.
2. Remove Exhaust Components: If replacement is necessary, unbolt the catalytic converter from the exhaust system using a socket set.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and align it with the exhaust system.
   • Secure it in place with new gaskets and bolts, torquing to the manufacturer's specifications.
4. Reconnect Exhaust System: Ensure all exhaust components are reattached properly and leaks are sealed.

4. Clear Codes and Test

1. Use OBD-II Scanner: Clear the P0420 code from the ECU.
2. Test Drive: Take the vehicle for a test drive to ensure the check engine light does not reappear and performance is restored.