how to troubleshoot P0420 code in Toyota Camry Eighth Generation (2018-present)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts during repair.
• Safety glasses and gloves should be worn for protection.

2. Inspect and Test Oxygen Sensors

• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Disconnect the electrical connectors of both oxygen sensors.
• Use a multimeter to test the voltage output of the upstream sensor (should fluctuate between 0.1V and 0.9V).
• Test the downstream sensor (should remain relatively stable; ideally around 0.5V).
• If the upstream sensor is faulty, replace it. If the downstream sensor shows erratic readings, replace it as well.

3. Check Catalytic Converter

• Inspect the catalytic converter for any physical signs of damage, such as dents or holes.
• Use a hammer to gently tap the converter; listen for rattling sounds, which indicate internal damage.
• If damaged, remove the catalytic converter by unbolting it from the exhaust system using a socket set.
• Replace with a new OEM catalytic converter and torque the bolts to the manufacturer’s specification (typically around 33-44 ft-lbs).

4. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Perform a test drive to allow the vehicle’s computer to re-evaluate the catalytic converter's performance.