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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the vehicle battery to ensure safety while working on electrical components.

2. Oxygen Sensor Replacement (if faulty)

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Using a socket wrench, carefully remove the defective sensor.
3. Apply anti-seize compound to the threads of the new oxygen sensor.
4. Install the new oxygen sensor and tighten it to the manufacturer’s specifications (usually around 30 lb-ft).
5. Reconnect the electrical connector of the oxygen sensor.

3. Catalytic Converter Inspection and Replacement (if needed)

1. Remove the exhaust pipe bolts connecting to the catalytic converter using a socket set.
2. Carefully detach the catalytic converter from the exhaust system.
3. Inspect the old catalytic converter for any signs of damage or clogging.
4. If replacement is required, install the new catalytic converter by reversing the removal steps.
5. Ensure all connections are tight and use a torque wrench to tighten bolts to the manufacturer’s specifications (typically around 30-50 lb-ft).

4. Reconnect and Test

1. Reconnect the vehicle battery.
2. Start the engine and allow it to reach operating temperature.
3. Check for any exhaust leaks and ensure all sensors are functioning.