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 cool.
• Disconnect the negative battery terminal to prevent electrical short circuits.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors:

   • Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.

2. Remove the Sensors:

   • Use an oxygen sensor socket or wrench to carefully unscrew and remove each oxygen sensor.
   • Take care not to damage the wiring harness.

3. Install New Sensors:

   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new upstream and downstream oxygen sensors and tighten to the manufacturer's specifications (usually around 30 Nm).

3. Inspect and Replace Catalytic Converter

1. Remove the Catalytic Converter:

   • Support the vehicle using jack stands.
   • Loosen the exhaust clamps or bolts securing the catalytic converter.
   • Remove any hangers or brackets and carefully detach the catalytic converter from the exhaust system.

2. Install New Catalytic Converter:

   • Position the new catalytic converter in place.
   • Secure it using the original or new clamps/bolts, ensuring proper alignment.
   • Torque all bolts to the manufacturer's specifications (typically around 30-40 Nm).

4. Reset the Check Engine Light

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.