how to fix the P0420 code on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands.
• Parts Required: New catalytic converter (if necessary), oxygen sensors (if faulty), exhaust gaskets.

2. Remove Faulty Components

• Step 1: Raise the vehicle using a jack and secure it with jack stands.
• Step 2: Disconnect the negative battery terminal to prevent electrical shorts.
• Step 3: Locate the catalytic converter and oxygen sensors; remove the oxygen sensors using the appropriate socket.
• Step 4: Unbolt the catalytic converter from the exhaust system; typically, there are two bolts at each end. Use a socket set for this task.
• Step 5: If necessary, remove any heat shields that may obstruct access to the catalytic converter.

3. Inspect and Replace

• Step 1: Inspect the old catalytic converter for any signs of clogging or damage.
• Step 2: If a replacement is necessary, install the new catalytic converter, ensuring the inlet and outlet are correctly aligned with the exhaust system.
• Step 3: Reinstall the oxygen sensors in their respective locations; torque them to the manufacturer's specifications (usually around 22 ft-lbs).
• Step 4: Reattach any heat shields that were removed.

4. Reconnect and Test

• Step 1: Reconnect the negative battery terminal.
• Step 2: Start the engine and allow it to reach operating temperature.
• Step 3: Use the OBD-II scanner to clear the P0420 code and monitor for any reoccurrence of the check engine light.