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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust gasket scraper.
• Parts Required: Oxygen sensor (if faulty), catalytic converter (if necessary), exhaust gaskets.
• Safety Warnings: Disconnect the battery before starting any electrical work; allow the exhaust system to cool before working on it.

2. Oxygen Sensor Replacement (if found faulty)

1. Disconnect the Battery

   • Remove the negative terminal from the battery to prevent electrical shorts.

2. Locate and Remove the Oxygen Sensor

   • Identify the oxygen sensor (upstream or downstream) based on the diagnostic findings.
   • Use a socket wrench to unscrew the sensor from the exhaust pipe or catalytic converter.

3. Install the New Oxygen Sensor

   • Apply anti-seize compound to the threads of the new oxygen sensor.
   • Screw the new sensor into place and tighten it to the manufacturer's specifications (typically around 30 ft-lbs).

3. Catalytic Converter Inspection/Replacement (if necessary)

1. Inspect the Catalytic Converter

   • Check for any signs of physical damage, excessive heat discoloration, or rattling sounds inside the converter.

2. Remove the Old Catalytic Converter

   • Use the socket set to remove the bolts securing the catalytic converter to the exhaust system.
   • Carefully detach the converter from the exhaust pipe.

3. Install the New Catalytic Converter

   • Position the new catalytic converter in place.
   • Secure it with bolts and gaskets, tightening to the manufacturer’s torque specifications (consult repair manual for details).

4. Reassemble Exhaust System

   • Ensure all components are properly aligned and secured.
   • Replace any gaskets that were disturbed during removal.