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

Solution

1. Preparation

• Gather all necessary 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: Oxygen sensor socket, ratchet, torque wrench.

• Remove the upstream (pre-catalytic converter) oxygen sensor:

  1. Locate the sensor near the exhaust manifold.
  2. Use an oxygen sensor socket to unscrew it.

• Install the new upstream oxygen sensor:

  1. Apply anti-seize compound on the threads of the new sensor.
  2. Torque the sensor to the manufacturer's specification (typically around 30-40 lb-ft).

• Repeat the process for the downstream (post-catalytic converter) oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, exhaust pipe cutter or saw, gasket scraper, torque wrench.
• Remove the catalytic converter:
  1. Disconnect the exhaust pipes using the appropriate wrenches.
  2. Cut or unbolt any clamps securing the catalytic converter.
  3. Remove the converter from its mounting points.
• Install the new catalytic converter:
  1. Ensure that the mating surfaces are clean; use a gasket scraper if necessary.
  2. Position the new converter in place and secure it using the original or new hardware.
  3. Torque any bolts to the specified value (typically around 20-25 lb-ft for exhaust bolts).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it run for a few minutes to ensure everything is functioning correctly.