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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.
• Raise the vehicle securely on jack stands for better access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Remove the O2 sensor(s) from the exhaust system using the O2 sensor socket. Apply penetrating oil if the sensor is stuck.
• Install the new O2 sensor(s) and torque to manufacturer's specifications (typically 30-40 lb-ft).
• Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust sealant, gaskets.
• Remove the exhaust pipes connected to the catalytic converter; this may involve removing bolts and clamps.
• Inspect the catalytic converter for physical damage or excessive carbon buildup.
• If replacing, install the new catalytic converter with new gaskets and exhaust sealant where necessary. Torque bolts to the manufacturer's specifications (refer to service manual for exact values).
• Reconnect the exhaust pipes and ensure all connections are secure.

4. Reset the ECU

• Reconnect the vehicle battery.
• Use the OBD-II scanner to erase the trouble codes and reset the ECU.
• Ensure all systems are operational after the reset.