how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety during repairs.
• Raise the vehicle and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors

   • The upstream (pre-catalytic) sensor is before the catalytic converter, and the downstream (post-catalytic) sensor is after it.

2. Remove Oxygen Sensor

   • Use an oxygen sensor socket to carefully unscrew the sensor from the exhaust pipe.
   • Tools Required: Oxygen sensor socket, ratchet wrench.

3. Install New Oxygen Sensor

   • Apply anti-seize compound on the threads of the new oxygen sensor.
   • Install the new sensor and torque it to the manufacturer’s specifications (usually around 30-35 ft-lbs).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Inspect Catalytic Converter

   • Check for physical damage, rattling, or discoloration that indicates overheating.

2. Remove Catalytic Converter

   • Disconnect any exhaust hangers and remove the bolts securing the catalytic converter to the exhaust system.
   • Tools Required: Socket set, breaker bar for stubborn bolts.

3. Install New Catalytic Converter

   • Position the new catalytic converter and secure it with bolts, ensuring all gaskets are in place.
   • Torque bolts to the manufacturer’s specifications (usually around 25-30 ft-lbs).

4. Reset the Check Engine Light

• Reconnect the battery and use an OBD-II scanner to erase the P0420 code from the ECU.

5. Test Drive the Vehicle

• Take the vehicle for a test drive to ensure that the check engine light does not reappear and the vehicle operates smoothly.