why does my Toyota Highlander Fourth Generation (2020-present) check engine light keep coming on?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface with the engine off.
• Disconnect the negative battery terminal to reset the ECU.

2. Addressing Error Codes

• Sub-step 1: Use the OBD-II scanner to retrieve and note the error codes.
• Sub-step 2: Research the codes to identify possible issues (e.g., P0420 for catalytic converter efficiency).
• Sub-step 3: Address the specific issue indicated by the codes (e.g., replace a faulty sensor).

3. Inspecting and Replacing Components

• Sub-step 1: If the gas cap is damaged, replace it with a new OEM part.
• Sub-step 2: If the air filter is clogged, remove the old filter and install a new one.
• Sub-step 3: For exhaust leaks, inspect piping and joints; replace gaskets or sections as needed.

4. Resetting the Check Engine Light

• Sub-step 1: Reconnect the negative battery terminal.
• Sub-step 2: Start the engine and allow it to reach operating temperature.
• Sub-step 3: Use the OBD-II scanner to clear the error codes.

5. Final Inspection

• Sub-step 1: Perform a visual inspection of the engine bay to ensure all connections are secure.
• Sub-step 2: Check for any signs of fluid leaks.
• Sub-step 3: Test drive the vehicle to monitor if the check engine light re-illuminates.

Tools Required:

• OBD-II scanner
• Socket set
• Screwdriver set
• Torque wrench (if needed for reassembly)

Parts Required:

• New gas cap (if applicable)
• Replacement air filter (if applicable)
• Exhaust gaskets or sections (if applicable)

Estimated Repair Time: 1-3 hours

Safety Warnings:

• Disconnect battery before working on electrical systems.
• Allow engine to cool before inspecting engine components.