why is my Toyota Corolla E140 (2006-2013) check engine light on P0420

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet and extension.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Unplug the electrical connectors from each sensor.
  3. Use the O2 sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install the new sensors and tighten them to the manufacturer’s specifications (usually around 30-40 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, cutting tool (if necessary), exhaust gasket.
• Sub-steps:
  1. Inspect the catalytic converter for any physical damage or signs of clogging.
  2. If replacement is needed, remove the exhaust pipes connected to the catalytic converter.
  3. Cut the exhaust pipes if they are rusted or corroded, and remove the old catalytic converter.
  4. Install the new catalytic converter, using new gaskets as necessary.
  5. Tighten all bolts to the manufacturer’s recommended torque specifications.

4. Reset the Check Engine Light

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery after all repairs are complete.
  2. Use the OBD-II scanner to clear the trouble codes from the vehicle's computer.