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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery by removing the negative terminal.
• Allow the exhaust system to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter
• Remove the upstream oxygen sensor (pre-catalytic converter) by:
  • Using the O2 sensor socket to turn counter-clockwise.
  • Disconnect the electrical connector carefully.
• Install the new upstream oxygen sensor:
  • Hand-tighten it before using the torque wrench (usually to 30 ft-lbs).
  • Reconnect the electrical connector.
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tools
• Remove the exhaust pipe connected to the catalytic converter by:
  • Unbolting the flange and any hangers.
  • Carefully lowering the exhaust system.
• Inspect the catalytic converter for physical damage or clogging.
• If replacement is necessary, remove the old catalytic converter by:
  • Unbolting it from the exhaust manifold and the exhaust pipe.
• Install the new catalytic converter:
  • Position it correctly and hand-tighten the bolts.
  • Torque the bolts to the manufacturer’s specifications (typically around 30-40 ft-lbs).
• Reattach the exhaust system and hangers securely.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it idle for a few minutes.