why does my Toyota Highlander Third Generation (2014-2019) have a service engine light on

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical systems.
• Allow the engine to cool if it has been running.

2. Addressing Error Codes

• Sub-step 1: Based on the OBD-II scanner results, identify the specific issue (e.g., P0420 for catalyst efficiency).
• Sub-step 2: Research the trouble code to understand the possible causes.
• Sub-step 3: If necessary, replace faulty components identified by the error code (e.g., oxygen sensor, catalytic converter).

3. Inspect and Repair

• Sub-step 1: If a sensor is faulty, remove it using the appropriate socket or wrench.
• Sub-step 2: Install the new sensor, ensuring it is properly torqued to manufacturer specifications (typically 30-50 ft-lbs for sensors).
• Sub-step 3: If fluid levels were low, top them off with OEM recommended fluids.

4. Clear Codes and Test

• 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 monitor for any warning lights.