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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle using jack stands for safety.

2. Inspect and Replace Components

A. Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket to unscrew the sensor from the exhaust manifold.
   • Disconnect the electrical connector.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads.
   • Torque to manufacturer's specifications (typically around 30 ft-lbs).
3. Repeat for the downstream oxygen sensor.

B. Catalytic Converter

1. Inspect the catalytic converter:
   • Check for physical damage, clogs, or signs of overheating.
2. If replacement is necessary:
   • Remove the exhaust pipe connected to the catalytic converter using a socket set.
   • Remove any securing bolts and hangers.
   • Install a new catalytic converter, ensuring proper alignment.
   • Torque bolts to manufacturer specifications (typically around 30-40 ft-lbs).

3. Reconnect Components

• Reattach any disconnected sensors and electrical connectors.
• Reconnect the battery terminals.

4. Clear Error Codes

• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.