how to fix P0420 code on my Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

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

2. Inspect the Oxygen Sensors

• Tools Required: OBD-II scanner, multimeter
• Remove the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Use the multimeter to check the voltage output of the upstream sensor; it should fluctuate between 0.1V to 0.9V.
• Check the downstream sensor; it should have less fluctuation than the upstream sensor.
• If the upstream sensor is faulty, replace it.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket
• Remove any heat shields or brackets securing the catalytic converter.
• Disconnect the exhaust pipes leading to and from the catalytic converter.
• Remove the catalytic converter from the vehicle.
• Inspect the old catalytic converter for physical damage or clogging.
• Install the new catalytic converter, ensuring proper alignment and secure it with the correct torque specifications (usually around 30-50 lb-ft).
• Replace any gaskets or seals to prevent exhaust leaks.

4. Reinstall Oxygen Sensors

• Reinstall the upstream and downstream oxygen sensors in their respective positions.
• Ensure they are tightened to manufacturer specifications (typically around 30 lb-ft).

5. Reset the Engine Control Module (ECM)

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's memory.