how to fix P0420 code on 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 negative battery terminal.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the upstream sensor and inspect it for carbon buildup.
  4. Install the new upstream sensor, torque to manufacturer's specification (typically 30-40 lb-ft).
  5. Repeat the process for the downstream sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Sub-steps:
  1. Inspect the catalytic converter for any signs of physical damage, such as dents or rust.
  2. Disconnect the exhaust pipes on either side of the catalytic converter using the socket set.
  3. Remove any hangers holding the catalytic converter in place using the exhaust hanger removal tool.
  4. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  5. Torque the bolts to manufacturer's specifications (refer to service manual typically around 25-30 lb-ft).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.

5. Test Drive

• Perform a test drive to ensure the check engine light remains off and that the vehicle operates smoothly.