how to fix P0420 code in Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on exhaust components.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an O2 sensor socket and ratchet 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 it into place and tighten it to the manufacturer's specification (typically around 30 ft-lbs).
   • Reconnect the electrical connector.
3. Repeat for the downstream oxygen sensor, located after the catalytic converter.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:
   • Use a socket set to loosen the bolts securing the converter to the exhaust system.
   • Disconnect any heat shields or brackets attached to the converter.
2. Install the new catalytic converter:
   • Position the new converter and secure it with bolts to the exhaust system.
   • Ensure all gaskets are replaced to prevent leaks.
   • Torque bolts to the manufacturer's specifications (check service manual for specific values).

4. Reconnect Battery and Clear Codes

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