how to fix P0420 code in 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.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, jack and jack stands.
• Safety Warnings: Disconnect the battery before working on electrical systems and allow the engine to cool before inspection.

2. Inspect and Test Oxygen Sensors

• Remove the upstream and downstream oxygen sensors using the socket set.
• Use a multimeter to test the voltage output of the upstream sensor. It should fluctuate between 0.1V and 0.9V. If it does not, replace the sensor.
• Check the downstream sensor for similar voltage readings. If it is stuck at a constant value, it may also need replacement.

3. Inspect and Replace Catalytic Converter (if necessary)

• If both oxygen sensors are functioning properly, proceed to inspect the catalytic converter.
• Remove the exhaust pipes connected to the catalytic converter using the socket set. Pay attention to any gaskets that may need replacement.
• Visually inspect the catalytic converter for any signs of damage or clogging. If it appears damaged or clogged, replace it with a new unit.
• Install the new catalytic converter, ensuring to torque all bolts to the manufacturer’s specifications.

4. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the check engine codes.
• Start the vehicle and allow it to reach operating temperature.
• Take the vehicle for a test drive, monitoring the performance and checking for the reactivation of the check engine light.