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

Solution

1. Preparation

• Gather tools and parts. Disconnect the battery.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, exhaust gas temperature probe, safety glasses, gloves.

2. Inspect and Replace Oxygen Sensors

1. Locate the pre-catalytic and post-catalytic oxygen sensors.
2. Disconnect the electrical connectors from both oxygen sensors.
3. Use an O2 sensor socket to remove the old sensors.
4. Install the new oxygen sensors and torque to the manufacturer's specifications (typically 30-40 lb-ft).
5. Reconnect the electrical connectors ensuring a secure fit.

3. Inspect and Replace Catalytic Converter

1. Evaluate the catalytic converter for visible damage or blockage.
2. If replacement is necessary, unbolt the catalytic converter from the exhaust system using a socket set.
3. Remove any heat shields if applicable.
4. Install the new catalytic converter, ensuring proper alignment and securing with bolts to the specified torque (generally 30-40 lb-ft).
5. Reinstall any heat shields.

4. Reset Engine Control Module (ECM)

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code from the ECM.
3. Perform a drive cycle to allow the system to monitor the catalytic converter's performance.