how to fix P0420 code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors.
2. Using a socket wrench, carefully remove the upstream oxygen sensor.
   • Tools Required: Oxygen sensor socket, ratchet, and extension.
   • Safety Warning: Wear gloves to protect from exhaust residue.
3. Install the new upstream oxygen sensor and torque to manufacturer specifications (typically around 30 ft-lbs).
4. Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

1. Remove the exhaust pipe connecting to the catalytic converter.
   • Tools Required: Socket set, penetrating oil (if rusted).
2. Inspect the catalytic converter for any signs of damage or clogging; replace if necessary.
3. Install the new catalytic converter and ensure all gaskets are in good condition.
4. Reattach the exhaust pipe and torque to proper specifications.

4. Clear Codes and Test Drive

1. Reconnect the battery.
2. Use the OBD-II scanner to clear the P0420 code.
3. Perform a test drive to monitor for any reoccurrence of the check engine light.