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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent any electrical shorts.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors using the O2 sensor socket.
• Inspect the sensors for any damage or contamination.
• Replace the oxygen sensors if they are faulty or worn out, ensuring they are torqued to manufacturer specifications (typically around 30 ft-lbs).

3. Examine and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust hangers tool, cutting tool (if needed for old exhaust).
• If the catalytic converter is found to be faulty, remove it by unbolting it from the exhaust manifold and the exhaust pipe.
• If necessary, cut the exhaust pipes to facilitate removal.
• Install the new catalytic converter in the reverse order of removal, ensuring proper alignment and securing all bolts to the specified torque.

4. Clear Codes and Test

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Perform a test drive to ensure that the check engine light does not return.