how to fix P0420 code in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to prevent electrical shocks.
• Raise the vehicle securely using jack stands.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and the downstream (post-catalytic) oxygen sensor.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an oxygen sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install the new oxygen sensors by reversing the removal process. Ensure they are properly torqued to manufacturer specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors to both sensors.

3. Inspect or Replace the Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for signs of damage, such as dents or rust.
  2. If defective, remove the catalytic converter by loosening the bolts on both ends using a socket set.
  3. Install the new catalytic converter in place, ensuring the exhaust gaskets are in good condition.
  4. Torque the bolts to manufacturer specifications (usually between 30-35 lb-ft).

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code.
  3. Test drive the vehicle under various conditions to ensure the check engine light does not reappear.

Tools Required:

• OBD-II scanner
• Oxygen sensor socket
• Socket set
• Torque wrench
• Jack and jack stands
• Multimeter

Parts Required:

• Upstream oxygen sensor (if required)
• Downstream oxygen sensor (if required)
• Catalytic converter (if needed)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before working on the exhaust system to prevent burns.