how to fix the check engine light on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter
• Ensure the vehicle is parked on a level surface and the engine is turned off.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Address Error Codes

• Sub-steps:
  1. If the OBD-II scanner shows codes related to the catalytic converter (e.g., P0420), check for exhaust leaks and inspect the catalytic converter.
  2. For ignition-related codes (e.g., P0300), replace faulty spark plugs or ignition coils as needed.
  3. If the code indicates an O2 sensor issue (e.g., P0131), locate the sensor and inspect its wiring and connector for damage; replace if necessary.

3. Inspect and Replace Gas Cap

• Sub-steps:
  1. Remove the gas cap and inspect the rubber seal for cracks.
  2. Clean the sealing surface on the filler neck.
  3. If the gas cap is damaged, replace it with a new one.

4. Check and Replace Spark Plugs/Coils

• Sub-steps:
  1. Remove the ignition coil covers using a socket set.
  2. Inspect the spark plugs for wear; replace them if they appear worn or damaged.
  3. If coils show signs of damage, replace them as well. Torque the new spark plugs to manufacturer specifications (usually around 13-15 lb-ft).

5. Inspect Air Filter

• Sub-steps:
  1. Open the air filter housing and remove the old air filter.
  2. Inspect for dirt and debris; install a new air filter if necessary.

6. Inspect Vacuum Hoses

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, splits, or disconnections.
  2. Replace any damaged vacuum hoses with new ones.