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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: The upstream sensor is typically located before the catalytic converter, and the downstream one is after.
2. Remove the Oxygen Sensors:
   • Use an oxygen sensor socket or a wrench to unscrew the upstream and downstream sensors.
   • Disconnect the electrical connectors for both sensors.
3. Install New Oxygen Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the upstream sensor first, followed by the downstream sensor, ensuring they are tightened to the manufacturer's specifications (usually around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

1. Remove Exhaust Components: If the catalytic converter needs replacing, remove the exhaust components connected to it using a socket set.
2. Remove the Catalytic Converter:
   • Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
   • Carefully detach it from its mounting points.
3. Install the New Catalytic Converter:
   • Position the new catalytic converter in place.
   • Secure it by bolting it to the exhaust manifold and exhaust pipe, ensuring all connections are tight and leak-free.
   • Use a torque wrench to tighten bolts to the manufacturer's specifications.

4. Final Steps

• Reconnect the battery.
• Clear the P0420 code using the OBD-II scanner.
• Start the engine and let it run for a few minutes to check for leaks.