how to fix P0420 code on Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety during the repair process.

2. Inspect and Clean Sensors

• Tools Required: O2 sensor socket, cleaning solvent.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for carbon buildup or damage. Clean the sensors using a suitable cleaning solvent or replace if necessary.

3. Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, torque wrench.
• Install new oxygen sensors if the old ones are defective.
• Torque the sensors to the manufacturer's specifications (typically around 30 ft-lbs).
• Reconnect the wiring harness to the sensors.

4. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust pipe cutter (if needed).
• If the catalytic converter is damaged or inefficient, remove it by unbolting it from the exhaust pipes.
• Install the new catalytic converter, ensuring proper alignment and fitting.
• Torque the bolts to the manufacturer's specifications.

5. Reassemble and Reconnect Battery

• Reconnect the battery terminals.
• Ensure all connections are secure and components are reinstalled correctly.