how to fix the P0420 code in my Toyota Corolla E170 (2013-2019) engine?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool completely before proceeding.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:

   • Use an oxygen sensor socket or wrench to carefully unscrew the sensor.
   • Disconnect the electrical connector.

2. Install the new upstream oxygen sensor:

   • Apply anti-seize compound to the threads of the new sensor.
   • Screw it into place and tighten to manufacturer specifications (typically 30-40 ft-lbs).
   • Reconnect the electrical connector.

3. Repeat for the downstream oxygen sensor if necessary:

   • Follow the same steps to remove and replace the downstream sensor.

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

1. Remove the exhaust pipe:

   • Loosen the bolts connecting the exhaust pipe to the catalytic converter using a socket set.
   • Carefully detach the exhaust pipe from the converter.

2. Remove the catalytic converter:

   • Unscrew the bolts or nuts securing the catalytic converter to the exhaust manifold.
   • Take out the catalytic converter from the vehicle.

3. Install the new catalytic converter:

   • Position the new catalytic converter in place and secure it with bolts/nuts as per manufacturer specifications (typically 30-40 ft-lbs).
   • Reattach the exhaust pipe to the catalytic converter.

4. Clear the Codes and Test Drive

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code from the ECU.
3. Test drive the vehicle to monitor performance and check if the check engine light returns.