how to fix P0420 code on my Toyota Camry Eighth Generation (2018-present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Safety gear: gloves and safety glasses.
• Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Disconnect the wiring harness from each oxygen sensor.
• Using the O2 sensor socket, carefully remove the sensors from the exhaust system.
• Inspect the threads for damage; clean the mounting area.
• Install the new oxygen sensors, tightening them to the manufacturer's specifications (typically around 30-35 lb-ft).
• Reconnect the wiring harness.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter.
• Raise the vehicle using the jack and secure it on jack stands.
• Inspect the catalytic converter for blockages or physical damage.
• If replacement is necessary, use the exhaust pipe cutter to remove the old catalytic converter.
• Install the new catalytic converter, ensuring proper alignment with exhaust hangers.
• Tighten all connections to the manufacturer's torque specifications (typically around 30-40 lb-ft).

4. Clear Codes and Test

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and let it reach normal operating temperature.
• Perform a test drive under various conditions to ensure the check engine light does not reappear.