how to fix P0420 code on Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety while working on the vehicle.
• Raise the vehicle using a jack and secure it with jack stands to access the exhaust components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench

• Remove the upstream oxygen sensor from the exhaust manifold:

  1. Locate the upstream oxygen sensor.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust manifold.
  3. Disconnect the electrical connector from the sensor.

• Install the new upstream oxygen sensor:

  1. Apply anti-seize compound to the threads of the new sensor.
  2. Connect the electrical connector and install the sensor into the manifold, tightening to manufacturer's torque specifications (usually around 30 lb-ft).

• Repeat the above steps for the downstream oxygen sensor if it has also been diagnosed as faulty.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• Remove the catalytic converter:
  1. Locate the catalytic converter in the exhaust system.
  2. Disconnect any mounting brackets or exhaust hangers.
  3. Remove the bolts securing the catalytic converter to the exhaust piping.
  4. Carefully remove the catalytic converter from its position.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place.
  2. Secure it with the bolts and tighten to manufacturer's specifications (typically around 40 lb-ft).
  3. Reattach any exhaust hangers or brackets.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear any trouble codes from the vehicle’s computer.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to ensure the check engine light does not reappear and to confirm proper operation.