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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts or shocks.
• Raise the vehicle securely on jack stands for access to the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor (O2 Sensor 1):
   • Disconnect the electrical connector.
   • Use an O2 sensor socket to unscrew and remove the sensor.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Screw in the new sensor and tighten it to manufacturer specifications (typically around 30 ft-lbs).
   • Reconnect the electrical connector.
3. Repeat for the downstream oxygen sensor (O2 Sensor 2) if necessary.

3. Inspect and Replace the Catalytic Converter

1. Remove the exhaust components:
   • Disconnect the exhaust pipe from the catalytic converter using a socket or wrench.
   • Remove any bolts or clamps securing the catalytic converter to the exhaust system.
2. Inspect the catalytic converter for any external damage or blockage.
3. Install the new catalytic converter:
   • Position the new converter in place and secure it using the original bolts or clamps.
   • Torque the bolts to manufacturer specifications (typically around 30-40 ft-lbs).
4. Reattach the exhaust pipe and ensure all connections are tight.

4. Reset the Engine Control Module (ECM)

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECM.

5. Test Drive the Vehicle

• Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor engine performance.