how to fix P0420 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Sub-steps:
  1. Use an OBD-II scanner to confirm that the upstream and downstream oxygen sensors are functioning correctly.
  2. If readings indicate faulty operation, locate the sensors (typically near the exhaust manifold and after the catalytic converter).
  3. Unplug the electrical connectors from the faulty oxygen sensors.
  4. Using a socket wrench, remove the sensors from their mounting locations.
  5. Install new oxygen sensors, applying anti-seize compound on the threads if required.
  6. Torque the sensors to the manufacturer’s specifications (usually around 30 lb-ft).
  7. Reconnect the electrical connectors and ensure they are secure.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Visually inspect the catalytic converter for any physical damage or blockage.
  2. If damaged, remove the exhaust pipe connected to the catalytic converter using a socket set.
  3. Remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque the bolts to the manufacturer's specifications (usually around 40 lb-ft).
  6. Reattach the exhaust pipe and ensure all connections are tight and leak-free.

4. Reconnect Battery

• Reconnect the battery terminals securely after all repairs are completed.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Anti-seize compound (if replacing sensors)

Parts Required:

• Upstream oxygen sensor
• Downstream oxygen sensor
• Catalytic converter (if needed)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the exhaust system to cool down before working on it to avoid burns.