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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket to unscrew the sensor.
   • Disconnect the electrical connector.
2. Remove the downstream oxygen sensor:
   • Repeat the process for the downstream sensor.
3. Install new oxygen sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Torque upstream sensor to manufacturer specifications (typically 30-40 lb-ft).
   • Torque downstream sensor similarly.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:
   • Loosen and remove the nuts/bolts securing it to the exhaust manifold and exhaust pipe using a socket set.
   • Carefully detach the catalytic converter from the exhaust system.
2. Inspect the old catalytic converter:
   • Check for signs of damage, clogging, or melting.
3. Install the new catalytic converter:
   • Position the new converter in place and align it with the exhaust system.
   • Secure it with nuts/bolts, torquing to manufacturer specifications.
   • Ensure all gaskets are replaced to prevent leaks.

4. Check for Exhaust Leaks

• Start the engine and inspect for any exhaust leaks around the newly installed components.
• If leaks are found, re-tighten connections or replace gaskets as necessary.

5. Reconnect Battery and Clear Codes

• Reconnect the battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.