my Toyota Highlander Fourth Generation (2020-present) check engine light is on what does it mean

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to avoid electrical shorts during inspection.
• Allow the engine to cool if it has been running.

2. Address Fault Codes

• Sub-step 1: Using the OBD-II scanner, retrieve the specific error codes.
• Sub-step 2: Research the error codes to determine the underlying issue (e.g., P0420 for catalytic converter efficiency).
• Sub-step 3: If the issue is related to a faulty sensor or component, order the necessary replacement parts.

3. Replace Components

• Sub-step 1: For a faulty gas cap, simply replace it with a new one.
• Sub-step 2: If spark plugs are worn, remove the ignition coils, and replace each spark plug with a new OEM part (typically torque to 13 lb-ft).
• Sub-step 3: For defective oxygen sensors, locate the sensor, disconnect the wiring harness, and unscrew it using a socket wrench. Install the new sensor, ensuring it is torqued according to specifications (usually around 30 lb-ft).

4. Clear Codes and Reconnect

• Sub-step 1: Reconnect the battery.
• Sub-step 2: Use the OBD-II scanner to clear the error codes.
• Sub-step 3: Start the engine and verify that the check engine light remains off.