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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery before starting work to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Unplug the electrical connectors from both sensors.
  3. Use the O2 sensor socket to unscrew the upstream O2 sensor and replace it with a new one.
  4. Repeat the process for the downstream O2 sensor if necessary.
  5. Torque the sensors to the manufacturer’s specified value (typically around 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack stands, exhaust gasket, torque wrench.
• Sub-steps:
  1. Safely lift the vehicle using jack stands.
  2. Remove any heat shields or covers obstructing access to the catalytic converter.
  3. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
  4. Inspect the old catalytic converter for any signs of damage or clogging.
  5. Install the new catalytic converter with a new exhaust gasket, ensuring all bolts are torqued to the manufacturer’s specifications.
  6. Reinstall any heat shields or covers.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code and any related codes.