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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the engine to cool down completely before starting work.

2. Inspect and Repair Exhaust System

• Inspect for Leaks:

  • Visually check the exhaust manifold, pipes, and joints for any signs of leaks.
  • Use a smoke machine if necessary to identify leaks.

• Repair Leaks:

  • If leaks are found, replace damaged sections of the exhaust system or use exhaust sealant as needed.

3. Replace Oxygen Sensors

• Remove the Old Sensors:

  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Use an O2 sensor socket to remove the sensors from the exhaust pipes.

• Install New Sensors:

  • Apply anti-seize compound to the threads of the new sensors.
  • Install the new sensors by threading them into place, and tighten to the manufacturer’s specifications (typically around 30-35 Nm).

4. Catalytic Converter Inspection/Replacement

• Inspect the Catalytic Converter:

  • Check for blockages or damage. If it’s damaged or clogged, replacement is necessary.

• Replace the Catalytic Converter:

  • Disconnect any hangers or brackets holding the catalytic converter in place.
  • Remove the bolts connecting it to the exhaust system using a socket set.
  • Install the new catalytic converter, ensuring that all gaskets are in place and secure it with bolts to the specified torque (typically around 40-50 Nm).

5. Final Checks

• Reconnect the negative battery terminal.
• Clear the P0420 code using an OBD-II scanner.