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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench

• Remove the upstream oxygen sensor:

  1. Locate the upstream O2 sensor (usually found before the catalytic converter).
  2. Use the O2 sensor socket to loosen and remove the sensor.
  3. Install the new upstream O2 sensor and torque it to manufacturer specifications (typically 30 Nm).

• Remove the downstream oxygen sensor (if needed):

  1. Locate the downstream O2 sensor (usually after the catalytic converter).
  2. Use the O2 sensor socket to remove it.
  3. Install the new downstream O2 sensor and torque it to manufacturer specifications (typically 30 Nm).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if applicable)

• Remove the catalytic converter:

  1. Disconnect any heat shields covering the catalytic converter.
  2. Remove the bolts or clamps securing the catalytic converter to the exhaust system using appropriate sockets.
  3. Carefully remove the catalytic converter from the exhaust system.

• Install the new catalytic converter:

  1. Position the new catalytic converter in place.
  2. Secure it with bolts or clamps, ensuring proper alignment and sealing.
  3. Torque the bolts to manufacturer specifications (typically around 40-50 Nm).

4. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.
• Clear any stored codes using the OBD-II scanner and perform a test drive to ensure the code does not reappear.