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 issues.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and extension.
• Remove the upstream (pre-catalytic) oxygen sensor:
  • Locate the sensor on the exhaust manifold.
  • Use the O2 sensor socket to unscrew and remove it.
• Install the new upstream oxygen sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Install and torque to manufacturer specifications (typically around 30 ft-lbs).
• Repeat the process for the downstream (post-catalytic) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Remove the exhaust pipe sections connected to the catalytic converter:
  • Loosen and remove the bolts securing the exhaust flanges.
  • Cut the exhaust pipe if it cannot be removed easily.
• Remove the catalytic converter:
  • Unbolt the converter from the exhaust manifold and the downstream pipe.
  • Inspect for physical damage or blockage.
• Install the new catalytic converter:
  • Position and secure it with bolts to the exhaust manifold and downstream pipe.
  • Torque bolts to manufacturer specifications (usually around 30-35 ft-lbs).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the ECM.