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

Solution

1. Preparation

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

2. Inspect and Replace O2 Sensors

1. Locate the upstream and downstream O2 sensors on the exhaust manifold and catalytic converter.
2. Unplug the electrical connectors from both O2 sensors.
3. Use a socket wrench to remove the sensors from the exhaust system.
4. Install new O2 sensors in their respective locations, tightening to the manufacturer’s specified torque (typically around 30 lb-ft).
5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If the O2 sensors are functioning properly, inspect the catalytic converter.
2. If damaged or inefficient, remove the bolts securing the catalytic converter to the exhaust system.
3. Carefully lower the catalytic converter from its mounting position.
4. Install the new catalytic converter, ensuring proper alignment.
5. Secure it with the bolts, tightening to the specified torque (usually around 40 lb-ft).
6. Reconnect any exhaust hangers or brackets.

4. Reconnect Battery and Clear Codes

1. Reconnect the battery terminals.
2. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.