how to fix the P0420 code on my Toyota Corolla E170 (2013-2019)?

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, cleaning spray for MAF sensor.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust pipes.
  4. Install new oxygen sensors, ensuring to torque them to the manufacturer’s specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors to the new sensors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Sub-steps:
  1. Use a socket set to remove any bolts or clamps securing the catalytic converter.
  2. Carefully remove the catalytic converter from the exhaust system.
  3. Inspect the new catalytic converter for any shipping damage before installation.
  4. Install the new catalytic converter, ensuring to align it properly with the exhaust piping.
  5. Torque the bolts to the manufacturer’s specifications (usually around 30 ft-lbs).

4. Reset the Engine Control Unit (ECU)

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Drive the vehicle for a short period to allow the ECU to recalibrate.