how to fix P0420 code in Honda Accord 8th Generation (2008-2012)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the vehicle's battery to ensure safety.
• Allow the engine to cool down before starting work.

Tools Required:

• OBD-II scanner
• Multimeter
• Socket set
• Torque wrench
• Safety goggles
• Gloves

2. Inspect and Replace Oxygen Sensors

1. Locate the pre-catalytic and post-catalytic oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Use a socket wrench to carefully remove the sensors from the exhaust manifold (pre-catalytic) and the catalytic converter (post-catalytic).
4. Inspect the sensors for corrosion or damage; replace if necessary.
5. Install new oxygen sensors by threading them into their respective locations and tightening to manufacturer's torque specifications (typically around 30 lb-ft).
6. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If the catalytic converter is found to be damaged or blocked during inspection, it will need to be replaced.
2. Remove the exhaust pipes connected to the catalytic converter using a socket set.
3. Unbolt the catalytic converter from its mounting points; be careful not to damage surrounding components.
4. Install the new catalytic converter, ensuring a proper fit.
5. Reattach the exhaust pipes and tighten all bolts to the specified torque value.

4. Clear Codes and Test

1. Reconnect the vehicle's battery.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
3. Start the engine and let it idle for a few minutes.
4. Take the car for a test drive for about 20 minutes to allow the vehicle's computer to re-evaluate the catalytic converter efficiency.