how to fix P0420 code in Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the engine to cool completely before proceeding.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream oxygen sensor:
  1. Use an O2 sensor socket to unscrew the sensor from the exhaust manifold.
  2. Disconnect the electrical connector from the sensor.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Screw the new sensor into place and reconnect the electrical connector.
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the catalytic converter:
  1. Loosen and remove the bolts securing the catalytic converter to the exhaust pipe and manifold.
  2. Use the exhaust hanger removal tool to detach any hangers holding the converter.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place and secure it with bolts.
  2. Ensure all connections are tight and use a torque wrench to meet manufacturer specifications.
• Reconnect any exhaust hangers and inspect the alignment.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.
• Start the engine and allow it to reach operating temperature.