what does the P0420 code mean for my Toyota Highlander?

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Disconnect the battery to ensure safety while working on the electrical systems.
• Allow the exhaust system to cool if the vehicle has been running.

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 Sensors:
   • Use a socket or wrench to remove both oxygen sensors carefully.
   • Disconnect the electrical connectors from each sensor.
3. Install New Oxygen Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and reconnect the electrical connectors.
   • Torque the sensors to the manufacturer’s specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

1. Remove Exhaust Components:
   • Loosen the bolts securing the catalytic converter to the exhaust system using a socket set.
   • Carefully remove any hangers that may obstruct removal.
2. Install New Catalytic Converter:
   • Position the new catalytic converter into place and secure it with bolts.
   • Ensure all gaskets are in good condition, replacing them if necessary.
   • Torque the bolts to the manufacturer's specifications.

4. Reset the Engine Control Module (ECM)

1. Reconnect the Battery:
   • Reconnect the battery terminals securely.
2. Clear the Codes:
   • Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Test Drive:
   • Drive the vehicle for a certain distance to monitor whether the check engine light reappears.