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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Multimeter
• Exhaust backpressure gauge (if needed)
• Safety gloves and goggles

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Disconnect the sensors: Unplug the electrical connectors linked to both sensors.
3. Remove the sensors: Use a socket wrench to unscrew and remove the sensors from their respective locations.
4. Install new sensors:
   • Apply anti-seize compound to the threads of new sensors.
   • Screw in the new sensors by hand, then tighten with a torque wrench to manufacturer specifications (usually around 30 lb-ft).
5. Reconnect electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check for physical damage: Examine the catalytic converter for dents, rust, or other signs of damage.
2. Perform backpressure test:
   • Connect the exhaust backpressure gauge to the O2 sensor port.
   • Start the engine and observe the reading; values above 1.5 psi at idle may indicate a clogged converter.
3. Remove the catalytic converter:
   • Loosen the bolts securing the catalytic converter to the exhaust system.
   • Carefully detach it from the exhaust manifold and the exhaust pipe.
4. Install new catalytic converter:
   • Position the new converter in place and secure it with bolts.
   • Ensure all gaskets are properly aligned and in good condition.
   • Torque the bolts to manufacturer specifications.
5. Reconnect exhaust system.

4. Clear Codes and Test

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Start the engine and allow it to reach operating temperature.
4. Perform a test drive to ensure no codes reappear and that the engine runs smoothly.