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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, jack and jack stands, socket set, torque wrench.
• Disconnect the vehicle battery to ensure safety during repairs.

2. Inspect Exhaust System

• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Visually inspect the entire exhaust system for cracks, rust, or loose connections.
  3. Repair or replace any damaged sections of the exhaust.

3. Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-cat) and downstream (post-cat) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a multimeter to test the voltage output of the upstream sensor while the engine is running (should fluctuate between 0.1V and 0.9V).
  4. Measure the downstream sensor voltage; it should be steady if the catalytic converter is functioning correctly.
  5. Replace any faulty oxygen sensors.

4. Evaluate Catalytic Converter

• Sub-steps:
  1. Check the catalytic converter for physical damage or blockage.
  2. Measure the inlet and outlet temperatures using an infrared thermometer; a significant temperature drop indicates a failing catalytic converter.
  3. If inefficient, remove the old catalytic converter.
  4. Install a new catalytic converter, ensuring proper alignment and secure it with the appropriate torque specifications.

5. Reassemble and Test

• Sub-steps:
  1. Reconnect all electrical connectors and exhaust components removed during the process.
  2. Reconnect the vehicle battery.
  3. Start the engine and allow it to reach operating temperature.
  4. Clear any stored trouble codes using the OBD-II scanner.