how to resolve P0420 code in my Honda Accord 9th Generation (2013-2017)?

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust gas temperature (EGT) gauge.
• Safety Warnings: Disconnect the battery before working on electrical systems. Allow the engine to cool before touching any components.

2. Replace Faulty Oxygen Sensors

• Step 1: Locate the upstream and downstream oxygen sensors.
• Step 2: Disconnect the electrical connectors from the sensors.
• Step 3: Use an O2 sensor socket to remove the sensors from the exhaust system.
• Step 4: Install the new sensors by threading them into place and tightening them to the manufacturer's torque specification (usually around 30 ft-lbs).
• Step 5: Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Step 1: Remove any heat shields or brackets securing the catalytic converter using the socket set.
• Step 2: Unbolt the catalytic converter from the exhaust system.
• Step 3: Inspect the old catalytic converter for damage, clogging, or excessive carbon buildup.
• Step 4: Install the new catalytic converter, ensuring to align it properly with the exhaust system.
• Step 5: Torque the bolts to the specified value (typically around 30-40 ft-lbs).
• Step 6: Reinstall any heat shields or brackets removed during the process.