how to fix P0420 error code in my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and the downstream (post-catalytic) oxygen sensor.
  2. Using the O2 sensor socket, carefully remove the upstream sensor.
  3. Install the new upstream oxygen sensor and torque it to manufacturer's specifications (typically around 30-40 ft-lbs).
  4. Repeat the process for the downstream oxygen sensor if it is also faulty.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Sub-steps:
  1. Inspect the catalytic converter for any physical damage, such as cracks or severe discoloration.
  2. If damaged, remove the catalytic converter from the exhaust system using a socket set.
  3. Install the new catalytic converter and ensure all bolts are tightened to the specified torque (usually around 40-50 ft-lbs).
  4. Ensure all joints are sealed properly to prevent exhaust leaks.

4. Clear Error Codes

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 error code from the vehicle's computer.

5. Test Drive

• Sub-steps:
  1. Conduct a test drive to ensure that the check engine light does not reappear and the vehicle operates normally.