my Toyota Camry Eighth Generation (2018-present) has a check engine light and P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery’s negative terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Locate the upstream oxygen sensor (usually before the catalytic converter).
   • Use an oxygen sensor socket to unscrew and remove the sensor.
   • Inspect the sensor for any signs of damage or contamination.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Install and torque it to the manufacturer’s specifications (typically around 30 ft-lbs).
3. Remove the downstream oxygen sensor:
   • Locate the downstream oxygen sensor (usually after the catalytic converter).
   • Repeat the removal and inspection process as done for the upstream sensor.
4. Install the new downstream oxygen sensor:
   • Apply anti-seize compound and torque to the manufacturer’s specifications.

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

1. Remove the exhaust components:
   • Unbolt the exhaust pipe from both ends of the catalytic converter using a socket set.
   • Carefully remove the catalytic converter from the exhaust system.
2. Inspect the catalytic converter:
   • Check for signs of physical damage, clogging, or excessive soot build-up.
3. Install the new catalytic converter:
   • Position the new catalytic converter and secure it with bolts.
   • Ensure proper alignment and tighten to the specified torque (usually around 30-40 ft-lbs).
4. Reattach the exhaust system:
   • Reconnect any exhaust pipes and ensure all connections are secure.

4. Final Steps

• Reconnect the battery’s negative terminal.
• Start the engine and allow it to reach operating temperature.