how to diagnose P0420 code on Toyota Corolla E210 (2019-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Repair Exhaust Leaks

• Sub-step 1: Visually inspect the exhaust system, focusing on joints and gaskets.
• Sub-step 2: Use a smoke machine to find any leaks if necessary.
• Sub-step 3: Repair any leaks found with appropriate exhaust sealant or replace damaged components.

3. Replace Faulty Oxygen Sensors (if needed)

• Sub-step 1: Locate the upstream and downstream oxygen sensors.
• Sub-step 2: Remove the electrical connector from the sensor.
• Sub-step 3: Use an oxygen sensor socket to unscrew and remove the old sensor.
• Sub-step 4: Install the new sensor and reconnect the electrical connector, ensuring it is secure.

4. Replace Catalytic Converter (if necessary)

• Sub-step 1: Loosen the bolts securing the catalytic converter to the exhaust system.
• Sub-step 2: Remove the old catalytic converter and install the new one, following any specific torque specifications for the bolts.
• Sub-step 3: Reconnect any sensors or components removed during the process.

5. Reconnect Battery and Clear Codes

• Sub-step 1: Reconnect the battery terminals.
• Sub-step 2: Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.