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

Solution

1. Preparation

• Gather tools and parts as listed below.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use a socket wrench to remove the oxygen sensors.
  3. Install the new oxygen sensors, ensuring they are tightened to manufacturer specifications (usually 30 lb-ft).
  4. Reconnect the oxygen sensor connectors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Remove the exhaust pipe connected to the catalytic converter using a socket set and ratchet.
  2. Disconnect any heat shields or brackets securing the catalytic converter.
  3. Remove the catalytic converter from the vehicle.
  4. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  5. Reattach any heat shields or brackets and tighten all connections to manufacturer specifications.

4. Reset the ECU

• Sub-steps:
  1. Reconnect the negative terminal of the battery.
  2. Use an OBD-II scanner to clear the codes from the ECU.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Ratchet
• Oxygen sensor socket

Parts Required:

• Upstream oxygen sensor
• Downstream oxygen sensor
• Catalytic converter

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Allow the exhaust system to cool before working on it to avoid burns.
• Use safety goggles and gloves when handling exhaust components.