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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety while working on the vehicle.

2. Inspect and Repair Exhaust Leaks

• Tools Required: Socket set, torque wrench.
• Check the entire exhaust system for leaks, particularly around joints and gaskets.
• Tighten any loose bolts and replace gaskets if necessary.

3. Replace Faulty Oxygen Sensors (if needed)

• Tools Required: O2 sensor socket, torque wrench, anti-seize compound.
• Remove the upstream oxygen sensor using an O2 sensor socket.
• Install the new sensor, applying anti-seize compound to the threads and tightening it to the manufacturer’s specified torque (typically around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor if it’s faulty.

4. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torch (if rusted), exhaust clamp tool.
• Raise the vehicle safely on jack stands.
• Remove the exhaust pipes connected to the catalytic converter using a socket set.
• If the converter is rusted, use a torch to heat the bolts for easier removal.
• Install the new catalytic converter, securing it with the appropriate exhaust clamps and bolts, tightening them to the manufacturer’s specifications.

5. Reset the ECU

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