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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Remove the upstream oxygen sensor:
  • Use an oxygen sensor socket and ratchet to unscrew.
  • Disconnect the sensor's electrical connector.
• Install the new upstream oxygen sensor:
  • Apply anti-seize compound on the threads (if required).
  • Screw in the new sensor and connect the electrical connector.

3. Inspect or Replace Catalytic Converter

• Check for physical damage:
  • Examine the catalytic converter for dents, cracks, or excessive rust.
• If replacement is needed:
  • Remove the old catalytic converter:
    • Use a socket set to detach the mounting bolts or nuts connecting it to the exhaust system.
    • Remove any hangers or brackets that may be holding it in place.
  • Install the new catalytic converter:
    • Position the new converter in place and secure it with the mounting bolts/nuts to manufacturer specifications (usually around 25-30 lb-ft torque).
    • Reattach any hangers or brackets.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the system.

5. Test Drive

• Start the engine and let it idle for a few minutes.
• Take the vehicle for a test drive under different driving conditions to ensure the check engine light does not reappear.