why does my Toyota Highlander Third Generation (2014-2019) check engine light keep coming on?

Solution

1. Preparation

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

2. Address Fault Codes

• Sub-step 1: Refer to the OBD-II scanner results to identify the fault codes.
• Sub-step 2: Research the specific code(s) to understand the underlying issues (e.g., P0420 for catalytic converter efficiency).
• Sub-step 3: Make a plan for repairs based on the identified codes.

3. Replace Components (if necessary)

• Sub-step 1: If a faulty sensor (e.g., O2 sensor) is indicated, locate the sensor and remove it using a socket wrench.
• Sub-step 2: Install the new sensor and torque it to the manufacturer's specifications (typically around 30 lb-ft for O2 sensors).
• Sub-step 3: If the gas cap is faulty, replace it with an OEM or equivalent cap, ensuring a tight fit.

4. Reset Check Engine Light

• Sub-step 1: Reconnect the negative battery terminal after repairs.
• Sub-step 2: Use the OBD-II scanner to clear the fault codes from the system.
• Sub-step 3: Start the vehicle and check if the check engine light remains off.