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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Gather safety gear including gloves and safety glasses.

2. Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:

   • Use an oxygen sensor socket to carefully unscrew the sensor from the exhaust manifold.
   • Disconnect the wiring harness from the sensor.

2. Install the new upstream oxygen sensor:

   • Apply anti-seize compound to the threads of the new sensor.
   • Screw the new sensor into place and connect the wiring harness.

3. Remove the downstream oxygen sensor:

   • Use an oxygen sensor socket to unscrew the sensor located after the catalytic converter.
   • Disconnect the wiring harness from this sensor.

4. Install the new downstream oxygen sensor:

   • Apply anti-seize compound to the threads of the new sensor.
   • Screw the new sensor into place and connect the wiring harness.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the defective catalytic converter:
   • Unbolt the catalytic converter from the exhaust system using a socket set.
   • Carefully disconnect any hangers or brackets holding it in place.
2. Install the new catalytic converter:
   • Position the new catalytic converter in place.
   • Secure it with the bolts and any necessary hangers or brackets, ensuring all connections are tight.

4. Clear Error Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.