how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect Exhaust System

• Raise the vehicle using jack stands for access.
• Visually inspect the entire exhaust system from the manifold to the tailpipe for any cracks or holes.
• Use a smoke test if necessary to locate small leaks.

3. Replace Faulty Oxygen Sensors (if applicable)

• Disconnect the negative battery terminal.
• Locate the upstream and downstream oxygen sensors.
• Use an oxygen sensor socket to remove the faulty sensor.
• Install the new sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
• Reconnect the electrical connectors.

4. Replace Catalytic Converter (if needed)

• If the catalytic converter is confirmed faulty, remove the exhaust pipe bolts and any necessary hangers.
• Disconnect the exhaust system from the catalytic converter.
• Install the new catalytic converter, ensuring proper alignment.
• Torque the bolts to manufacturer specifications (typically around 25 ft-lbs).

5. Finalize and Check

• Reconnect the negative battery terminal.
• Start the engine and check for any exhaust leaks.
• Clear the P0420 code using the OBD-II scanner.