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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream (pre-catalytic converter) oxygen sensor using the O2 sensor socket.
  1. Disconnect the electrical connector.
  2. Install the new oxygen sensor and reconnect the electrical connector. Torque to manufacturer specifications (usually around 30 lb-ft).
• Repeat for the downstream (post-catalytic converter) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the exhaust pipe connections to the catalytic converter.
  1. Unbolt and remove any heat shields if necessary.
  2. Detach the catalytic converter from the exhaust manifold and the downstream exhaust pipe.
• Install the new catalytic converter:
  1. Position the new converter and secure it to the exhaust manifold and downstream pipe.
  2. Torque the bolts to specifications, typically around 25 lb-ft.
  3. Reinstall any heat shields that were removed.

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.