how to fix P0420 catalyst efficiency code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Remove the upstream oxygen sensor using the O2 sensor socket.
• Inspect the sensor for carbon buildup or damage.
• If defective, replace it with a new sensor, ensuring it is torqued to the manufacturer's specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream oxygen sensor if needed.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Loosen the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe using the socket set.
• Remove the old catalytic converter, taking care not to damage the exhaust flanges.
• Install the new catalytic converter, ensuring all gaskets are in place, and torque the bolts to the manufacturer’s specifications.
• Reinstall any exhaust hangers removed during the process.

4. Clear the Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.