how to fix P0420 error code in Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, socket set, torque wrench, jack stands, and safety goggles.
• Disconnect the battery to prevent electrical issues during repairs.

2. Inspect and Replace Oxygen Sensors

• Sub-step 1: Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Sub-step 2: Use a socket wrench to remove the old oxygen sensors from the exhaust pipe.
• Sub-step 3: Install the new oxygen sensors (ensure they are the correct type for your model) and torque to manufacturer specifications (usually around 30-40 ft-lbs).
• Sub-step 4: Reconnect the wiring harness to the new sensors.

3. Inspect and Replace Catalytic Converter

• Sub-step 1: Raise the vehicle using a jack and secure it with jack stands.
• Sub-step 2: Remove the exhaust components connected to the catalytic converter (flanges and brackets) using the socket set.
• Sub-step 3: Carefully remove the old catalytic converter from the vehicle.
• Sub-step 4: Install the new catalytic converter, ensuring proper alignment and sealing.
• Sub-step 5: Torque the bolts to the manufacturer's specifications and reattach any exhaust components.

4. Clear Error Codes

• Sub-step 1: Reconnect the battery.
• Sub-step 2: Use the OBD-II scanner to clear the P0420 error code from the system.
• Sub-step 3: Start the vehicle and let it idle to ensure no error codes reappear.