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

Solution

1. Preparation

• Gather necessary tools and replacement parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the Upstream Oxygen Sensor:
   • Use an oxygen sensor socket to unscrew the sensor.
   • Carefully disconnect the wiring harness.
3. Install New Upstream Oxygen Sensor:
   • Apply anti-seize compound to the threads of the new sensor.
   • Install and torque to manufacturer specifications (typically around 30 ft-lbs).
   • Reconnect the wiring harness.
4. Repeat for Downstream Oxygen Sensor: Follow the same steps to replace the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter (if needed)

1. Remove Exhaust Components: Remove any bolts or clamps securing the catalytic converter. Use a wrench or socket set.
2. Detach the Catalytic Converter: Carefully lower the catalytic converter from the exhaust system.
3. Install New Catalytic Converter:
   • Position the new catalytic converter and secure it with bolts or clamps.
   • Ensure all gaskets are replaced to prevent leaks.
4. Torque Bolts: Tighten all bolts to manufacturer specifications (check service manual for specific torque values).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's memory.