how to fix P0420 code in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Oxygen Sensors

1. Remove the wiring harness from the upstream (pre-catalytic converter) oxygen sensor.
2. Use a 22mm oxygen sensor socket to unscrew the sensor from the exhaust manifold.
3. Install the new oxygen sensor and torque it to manufacturer specifications (typically around 30 ft-lbs).
4. Reconnect the wiring harness.
5. Repeat steps 1-4 for the downstream (post-catalytic converter) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

1. Use a socket set to remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
2. Carefully remove the catalytic converter from the vehicle.
3. Inspect the old catalytic converter for damage or clogging.
4. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
5. Torque the bolts to manufacturer specifications (typically around 30-40 ft-lbs).
6. Reconnect any exhaust hangers or brackets that were removed.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use an OBD-II scanner to clear the P0420 code from the system.

5. Road Test

1. Start the engine and allow it to reach operating temperature.
2. Perform a road test to ensure that the vehicle runs smoothly.
3. Monitor for the return of the P0420 code using the OBD-II scanner.