how to fix P0420 catalyst efficiency code in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to avoid electrical shocks.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors of both oxygen sensors.
  3. Remove the sensors using a specialized oxygen sensor socket.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer’s specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Check and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Inspect the catalytic converter for any physical damage or blockage.
  2. If replacement is needed, unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  3. Remove and replace with a new catalytic converter, ensuring to use gaskets as needed.
  4. Torque the bolts to the manufacturer's specifications, typically around 40 lb-ft for exhaust connections.

4. Reset the ECU

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECU.
  3. Start the engine and allow it to idle for a few minutes.