how to fix P0420 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Inspect Oxygen Sensors:

  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Visually inspect for corrosion, damage, or loose connections.

• Replace Faulty Sensors:

  • If either sensor is faulty, use a socket wrench to remove it.
  • Install the new sensor and torque to manufacturer specifications (usually around 30 ft-lbs).
  • Reconnect the electrical connectors securely.

3. Check and Replace Catalytic Converter

• Inspect the Catalytic Converter:

  • Verify that the catalytic converter is not clogged or damaged. Tap lightly to listen for rattling noises indicating internal damage.

• Replace the Catalytic Converter (if necessary):

  • Disconnect the exhaust pipes from the catalytic converter using a socket set and remove any mounting bolts.
  • Install the new catalytic converter in the reverse order and ensure all connections are secure and leak-free.
  • Torque the bolts to the specified value (usually around 25 ft-lbs).

4. Reset the Engine Control Module (ECM)

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

5. Test Drive

• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure the check engine light does not return.