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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the exhaust system to cool before beginning work.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the Sensors: Use an oxygen sensor socket to carefully unscrew and remove both sensors.
3. Inspect the Sensors: Check for signs of corrosion or damage on the sensor connectors and wiring.
4. Install New Sensors: Apply anti-seize compound to the threads of the new sensors and install them, tightening to manufacturer specifications (typically around 30 ft-lbs).

3. Examine/Replace the Catalytic Converter

1. Remove the Exhaust Components: If the catalytic converter requires replacement, unbolt the exhaust pipe sections leading to and from the converter using a socket set.
2. Inspect the Converter: Check for physical damage or a rattling sound internally, indicating a failure.
3. Install the New Catalytic Converter: Position the new converter and secure it with the bolts, ensuring to use a new gasket if required. Torque bolts to manufacturer specifications (usually around 40-50 ft-lbs).

4. Reconnect Battery and Clear Codes

1. Reconnect the Negative Battery Terminal: Ensure the battery is securely connected.
2. Clear the Trouble Codes: Use an OBD-II scanner to reset the check engine light and clear any stored codes.