how to fix P0420 code on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety while working on electrical components.
• Raise the vehicle and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use the O2 sensor socket to remove the upstream oxygen sensor and inspect it for carbon buildup or damage.
  3. If the sensor is faulty, install the new oxygen sensor and torque to manufacturer specifications (typically around 30 Nm).
  4. Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Jack stands, socket set, torque wrench, exhaust gasket.
• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage, such as dents or rust.
  2. If replacement is needed, unbolt the catalytic converter from the exhaust pipes using the socket set.
  3. Remove the old exhaust gasket and clean the mating surfaces.
  4. Install the new catalytic converter with a new gasket and torque to specifications (usually around 40-50 Nm).

4. Reset the Engine Control Module (ECM)

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the engine and let it idle for a few minutes.