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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts during repair.
• Allow the exhaust system to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually before and after the catalytic converter).
  2. Using a socket wrench, carefully remove the upstream oxygen sensor from the exhaust manifold.
  3. Install a new oxygen sensor, ensuring to use anti-seize compound on the threads.
  4. Repeat the process for the downstream oxygen sensor if needed.

Tools Required:

• Oxygen sensor socket
• Socket wrench
• Anti-seize compound

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for signs of physical damage or blockage.
  2. If replacement is necessary, unbolt the catalytic converter from the exhaust system using a socket wrench.
  3. Install the new catalytic converter, making sure to tighten bolts to manufacturer specifications (usually around 30-40 ft-lbs).
  4. Reconnect all exhaust components and ensure there are no leaks.

Tools Required:

• Socket set
• Torque wrench