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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream oxygen sensor (pre-cat) using the O2 sensor socket.
  • Sub-steps:
    • Disconnect the electrical connector from the sensor.
    • Use the O2 sensor socket to unscrew the sensor and replace it with a new one.
    • Torque the new sensor to the manufacturer’s specification (typically around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor (post-cat) if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack stands, cutting torch (if needed), new gaskets.
• Raise the vehicle securely on jack stands and locate the catalytic converter.
  • Sub-steps:
    • Inspect for any physical damage or leaks.
    • If damaged, remove the exhaust bolts securing the catalytic converter and carefully detach it from the exhaust system.
    • Install a new catalytic converter, ensuring to use new gaskets and torque the bolts to manufacturer specifications.

4. Final Checks

• Reconnect the negative battery terminal.
• Start the engine and allow it to reach operating temperature.