how to fix P0420 code on Toyota Corolla E170 (2013-2019)

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 negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors (if faulty)

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Sensors:
   • Use an oxygen sensor socket and ratchet to unscrew the sensors from the exhaust manifold and catalytic converter.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new upstream and downstream oxygen sensors and tighten to the manufacturer’s specifications (typically around 30-40 ft-lbs).
4. Reconnect Electrical Connectors: Ensure the connectors are secure and free from corrosion.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Remove Exhaust Components:
   • Use a socket set to remove the bolts securing the catalytic converter to the exhaust manifold and exhaust pipe.
   • Carefully lower the catalytic converter from the vehicle.
2. Install New Catalytic Converter:
   • Position the new catalytic converter in place, ensuring proper alignment with exhaust gaskets.
   • Secure the bolts to the manufacturer’s torque specifications (typically around 30-35 ft-lbs).
3. Reconnect Exhaust Components: Reinstall any exhaust hangers or brackets that were removed.

4. Clear Codes and Test Drive

1. Reconnect Battery: Reconnect the negative battery terminal.
2. Clear the P0420 Code: Use the OBD-II scanner to clear the trouble codes.
3. Test Drive: Drive the vehicle for at least 20 minutes to allow the engine to reach operating temperature and monitor for any reoccurrence of the P0420 code.