how to fix P0420 catalyst efficiency code in Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Disconnect the sensor wiring harness.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Torque to manufacturer specifications (usually around 30 lb-ft).
• Repeat the process for the downstream (post-catalytic) oxygen sensor if needed.

3. Inspect and Repair Exhaust System

• Tools Required: Socket set, exhaust pipe cutter (if necessary), clamps.
• Examine the exhaust pipes for leaks:
  1. Use soapy water to identify leaks by bubbling.
  2. Tighten any loose connections or replace damaged sections of the exhaust.
• Replace any damaged exhaust gaskets or clamps to ensure a proper seal.

4. Check and Replace Catalytic Converter

• Tools Required: Wrench set, jack, jack stands.
• If the catalytic converter is damaged:
  1. Raise the vehicle safely using a jack and secure with jack stands.
  2. Remove the bolts securing the catalytic converter to the exhaust system.
  3. Remove the old catalytic converter and install the new one, ensuring proper alignment.
  4. Torque the bolts to manufacturer specifications.

5. Clear Codes and Test

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Start the vehicle and allow it to reach operating temperature.