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

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors

1. Disconnect the Battery: Remove the negative terminal to prevent electrical issues.
2. Locate the Oxygen Sensors: Find the upstream (pre-catalytic converter) and downstream (post-catalytic converter) sensors.
3. Remove the Sensors:
   • Use a socket wrench to unscrew the sensors.
   • Disconnect the wiring harness from each sensor.
4. Install New Sensors:
   • Apply anti-seize lubricant to the threads of the new sensors.
   • Install the new sensors, ensuring they are tightened to manufacturer specifications (typically 30 Nm).
   • Reconnect the wiring harness.

3. Inspect and Replace the Catalytic Converter

1. Check for Damage: Inspect the catalytic converter visually for any signs of damage or blockage.
2. Remove the Old Converter:
   • Use a socket set to unbolt the catalytic converter from the exhaust pipes.
   • Carefully lower and remove the converter from the vehicle.
3. Install the New Converter:
   • Position the new catalytic converter in place.
   • Secure it with bolts, tightening to the manufacturer's torque specifications.
4. Reconnect Exhaust System: Ensure all connections are tight and secure to prevent leaks.

4. Reset the Check Engine Light

1. Reconnect the Battery: Attach the negative terminal back to the battery.
2. Clear Error Codes: Use the OBD-II scanner to clear the P0420 code and any other stored codes.