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

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down before working on exhaust components.

2. Inspect and Repair Exhaust Leaks

• Tools Required: Socket set, torque wrench
• Inspect the exhaust system from the engine to the tailpipe.
• Tighten or replace any loose or damaged exhaust bolts and gaskets.
• If leaks are found, seal with exhaust pipe sealant or replace affected components.

3. Oxygen Sensor Replacement (if necessary)

• Tools Required: O2 sensor socket, torque wrench
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Disconnect the electrical connectors and unbolt the sensors from the exhaust.
• Install new sensors by threading them into the exhaust and tightening to the manufacturer’s torque specifications (typically around 30-35 ft-lbs).
• Reconnect the electrical connectors.

4. Catalytic Converter Replacement (if necessary)

• Tools Required: Socket set, oxygen sensor socket, torque wrench, cutting tool (if needed)
• Remove the exhaust system components leading to the catalytic converter (if applicable).
• Unbolt the catalytic converter from the exhaust system.
• Replace with a new catalytic converter, ensuring proper fitment.
• Tighten all bolts to manufacturer specifications and reconnect any removed components.

5. Reset the Engine Control Module (ECM)

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the ECM.
• Start the engine and allow it to reach operating temperature.