how to fix the check engine light for code P0420 on Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Disconnect the vehicle’s battery to prevent electrical issues.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Sensors:
   • Use an O2 sensor socket to carefully unscrew the sensors from the exhaust manifold and catalytic converter.
   • Avoid damaging the wiring harness.
3. Install New Sensors:
   • Apply anti-seize compound on the threads of the new sensors (if not pre-applied).
   • Screw in the new sensors and tighten them to the manufacturer's specifications (typically around 30 ft-lbs).
4. Reconnect Electrical Connectors: Ensure the connectors are seated properly and locked in place.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Examine the Catalytic Converter: Look for signs of physical damage, such as dents or rust.
2. Remove the Catalytic Converter:
   • Use a socket set to unbolt the catalytic converter from the exhaust system.
   • Check for any additional mounting brackets that may need removal.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place.
   • Tighten the bolts to the specified torque (typically around 30-40 ft-lbs).
   • Ensure all gaskets are replaced to prevent exhaust leaks.

4. Reconnect Battery and Reset Codes

• Reconnect the negative terminal of the battery.
• Use the OBD-II scanner to clear the check engine light and reset the vehicle's computer.