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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) oxygen sensor:
  • Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
  • Check the condition of the sensor and replace if necessary.
• Remove the downstream (post-catalytic) oxygen sensor:
  • Use the O2 sensor socket to unscrew the sensor from the catalytic converter.
  • Inspect and replace if faulty.
• Torque Specifications: Install new sensors to the manufacturer’s recommended torque value (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter (if applicable), gasket scraper, torque wrench.
• Raise the vehicle using a jack and secure it with jack stands.
• Remove the exhaust pipes connected to the catalytic converter:
  • Use a socket set to unbolt the flanges and remove any exhaust hangers.
• Inspect the catalytic converter for damage or clogging.
• If replacement is necessary:
  • Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  • Use new gaskets and securely tighten all bolts to the manufacturer’s torque specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.