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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the electrical systems.
• Allow the exhaust system to cool down before beginning work.

2. Inspect and Replace Oxygen Sensors (if faulty)

1. Locate the upstream and downstream oxygen sensors.
2. Disconnect the electrical connectors from both sensors.
3. Use a socket wrench to remove the sensors from the exhaust manifold and catalytic converter.
4. Install new oxygen sensors, ensuring to torque to manufacturer specifications (usually around 30 Nm, but verify with a service manual).
5. Reconnect the electrical connectors securely.

3. Replace the Catalytic Converter (if necessary)

1. Support the vehicle on jack stands to access the exhaust system.
2. Remove any heat shields or brackets securing the catalytic converter.
3. Disconnect the exhaust pipes from both ends of the catalytic converter using a socket set.
4. Remove the old catalytic converter and install the new one.
5. Reattach the exhaust pipes and heat shields, ensuring all fasteners are torqued to spec.

4. Clear Codes and Test Drive

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code from the ECU.
3. Start the engine and allow it to reach operating temperature.
4. Take the vehicle for a test drive under various conditions to ensure the check engine light does not reappear.