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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery before starting any repair.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the old sensors:
   • Use an O2 sensor socket to unscrew the sensors carefully.
   • Disconnect the wiring harness from each sensor.
3. Install new sensors:
   • Apply anti-seize compound on the threads of the new sensors.
   • Install the new sensors by hand first, then torque to manufacturer specifications (typically around 30 lb-ft).
   • Reconnect the wiring harness.

3. Inspect and Replace the Catalytic Converter

1. Remove the catalytic converter:
   • Loosen and remove the bolts or nuts securing the catalytic converter to the exhaust system using a socket set.
   • Carefully lower the catalytic converter from the vehicle.
2. Inspect the old catalytic converter for signs of clogging or damage; replace if necessary.
3. Install the new catalytic converter:
   • Position the new converter into place and secure it using the original or new hardware.
   • Torque the bolts to the specified value (usually around 30-40 lb-ft).
4. Reconnect the exhaust system: Ensure all connections are tight and there are no leaks.

4. Clear the Codes and Test

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code from the vehicle's memory.
3. Start the engine and allow it to reach operating temperature.
4. Take the vehicle for a test drive under various conditions to ensure proper operation.