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

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the battery to ensure safety during electrical work.

2. Inspect Oxygen Sensors

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors.
  • Disconnect the wiring harness from each sensor.
  • Test the sensors' resistance using a multimeter (should typically be around 2-4 ohms for heated sensors).
  • Replace any faulty sensors.
• Tools Required: Multimeter, socket set.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  • Raise the vehicle securely on jack stands.
  • Remove the heat shield if present.
  • Unbolt the catalytic converter from the exhaust system using a socket set.
  • Inspect the catalytic converter for blockages or damage.
  • Install the new catalytic converter and torque bolts to manufacturer specifications (usually around 30-40 lb-ft).
• Tools Required: Socket set, torque wrench.

4. Reconnect Battery and Clear Codes

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