how to fix P0420 code on Honda Accord 8th Generation (2008-2012)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the battery to avoid any electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the O2 Sensors
   • Identify the locations of the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Sensors
   • Use an O2 sensor socket to carefully unscrew both sensors from their respective locations.
   • Be cautious of any wiring attached to the sensors.
3. Install New O2 Sensors
   • Apply anti-seize compound to the threads of the new O2 sensors.
   • Install the new sensors and tighten to manufacturer specifications (typically 30-40 Nm).
4. Reconnect Wiring
   • Ensure that the wiring harnesses are securely connected to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Locate the Catalytic Converter
   • Find the catalytic converter under the vehicle along the exhaust system.
2. Remove Exhaust Components
   • Use a socket set to loosen and remove any bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
3. Inspect the Catalytic Converter
   • Check for any physical damage, signs of clogging, or melted internals.
4. Install New Catalytic Converter
   • Position the new catalytic converter in place and secure it with bolts.
   • Torque the bolts to manufacturer specifications (usually 40-50 Nm).
5. Reconnect Any Exhaust Components
   • Ensure all exhaust components are properly reattached and sealed.

4. Reconnect Battery and Clear Codes

1. Reconnect the Battery
   • Connect the negative terminal of the battery and ensure it is tightened.
2. Clear the Engine Codes
   • Use an OBD-II scanner to erase the P0420 code from the vehicle's computer.