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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use a socket wrench to remove the sensors.
3. Inspect the connectors for corrosion or damage; replace if necessary.
4. Install new oxygen sensors, ensuring they are tightly secured and the connectors are properly attached.

3. Inspect and Repair Exhaust System

1. Examine the entire exhaust system for leaks, cracks, or loose connections.
2. If damage is found, use a socket set to remove affected sections of the exhaust.
3. Replace damaged components (muffler, exhaust pipe, etc.) with OEM or high-quality aftermarket parts.
4. Reassemble the exhaust system and secure all connections.

4. Check and Replace the Catalytic Converter (if necessary)

1. If the catalytic converter appears damaged or contaminated, remove it by loosening the bolts securing it to the exhaust system.
2. Install a new catalytic converter, ensuring it meets OEM specifications.
3. Torque the bolts to the manufacturer’s specifications (typically around 30-40 ft-lbs).