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

Solution

1. Preparation

• Ensure the vehicle is parked on a flat surface, and the engine is cool.
• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical issues.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the wiring harness from both sensors.
  3. Use an O2 sensor socket to remove the sensors.
  4. Install new sensors, ensuring they are torqued to manufacturers’ specifications (typically around 30 ft-lbs).
  5. Reconnect the wiring harness.

Tools Required:

• OBD-II scanner
• Oxygen sensor socket
• Ratchet and socket set
• Torque wrench
• Multimeter

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. If the catalytic converter fails the backpressure test, remove it by unbolting the exhaust flange and any supporting brackets.
  2. Install the new catalytic converter, ensuring proper alignment.
  3. Torque the exhaust bolts to manufacturer specifications (typically around 30 ft-lbs).
  4. Reconnect any sensors or components removed during the process.

Tools Required:

• Socket set
• Torque wrench