how to fix P0420 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, jack and jack stands, thermal gun, multimeter.
• Disconnect the battery negative terminal to ensure safety while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors (usually near the exhaust manifold and after the catalytic converter).
2. Using a wrench, carefully disconnect the wiring harness from each sensor.
3. Remove the sensors using a socket wrench.
4. Install new oxygen sensors, ensuring to torque them to the manufacturer’s specifications (typically around 30 ft-lbs).
5. Reconnect the wiring harness to each sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

1. If the catalytic converter is faulty, raise the vehicle using jack stands.
2. Remove the exhaust heat shield (if applicable) by unscrewing bolts or clips.
3. Disconnect the exhaust pipe from the catalytic converter by removing the bolts or clamps with a socket set.
4. Remove the catalytic converter by unbolting it from the exhaust manifold.
5. Install the new catalytic converter by reversing the removal steps, ensuring all bolts are torqued to the manufacturer’s specifications.
6. Reinstall the exhaust heat shield.

4. Reset the Engine Control Module (ECM)

1. Reconnect the battery negative terminal.
2. Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Start the vehicle and allow it to reach normal operating temperature.