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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually found before and after the catalytic converter).
  2. Remove the connectors from both sensors.
  3. Using the O2 sensor socket, carefully unscrew the sensors from their mounting points.
  4. Install new sensors by screwing them in hand-tight, then torque to manufacturer's specifications (usually around 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Sub-steps:
  1. Visually inspect the catalytic converter for any obvious damage or blockages.
  2. If replacement is necessary, unbolt the exhaust flanges connecting the catalytic converter to the exhaust system.
  3. If needed, use an exhaust pipe cutter to remove the old catalytic converter.
  4. Position the new catalytic converter and secure it to the exhaust system with new gaskets.
  5. Torque the bolts to the specified torque value (usually around 25 lb-ft).

4. Final Steps

• Reconnect the negative battery terminal.
• Start the engine and let it idle for a few minutes to ensure everything is functioning correctly.
• Check for leaks in the exhaust system and listen for unusual noises.