how to fix a check engine light issue on my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Addressing Fault Codes

• Sub-step 1: Connect the OBD-II scanner and retrieve the trouble codes.
• Sub-step 2: Research the codes to identify the specific issue (e.g., P0420 for catalytic converter efficiency).
• Sub-step 3: Clear the codes from the system and re-check to see if they return after a drive cycle.

3. Inspect and Replace Components

• Sub-step 1: If the gas cap is faulty, replace it with a new OEM part.
• Sub-step 2: If vacuum leaks are detected, replace any damaged hoses or clamps.
• Sub-step 3: For air filter or spark plug issues, remove the old components and install new, manufacturer-recommended parts.

4. Electrical System Check

• Sub-step 1: Reconnect the battery terminal and ensure connections are tight.
• Sub-step 2: Use a multimeter to check the battery voltage; it should be around 12.6 volts at rest.
• Sub-step 3: If the battery is low, charge or replace it as necessary.

5. Final Assembly

• Sub-step 1: Ensure all components are securely fastened and installed correctly.
• Sub-step 2: Reconnect any components that were removed during inspection.
• Sub-step 3: Start the engine and monitor for any unusual noises or leaks.