how to diagnose P0301 code in Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is on a flat surface and the engine is cool.
• Disconnect the battery.

2. Replace Spark Plug and Ignition Coil

• Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Disconnect the ignition coil connector for cylinder 1.
  3. Remove the ignition coil by unscrewing the mounting bolts.
  4. Extract the spark plug using a spark plug socket.
  5. Install the new spark plug to the specified torque (typically 13-15 lb-ft).
  6. Reinstall the ignition coil and reconnect the harness.

3. Inspect and Replace Fuel Injector (if necessary)

• Sub-steps:
  1. Disconnect the fuel injector connector.
  2. Remove the retaining clips and pull out the fuel injector.
  3. Install the new fuel injector, ensuring it seats correctly.
  4. Reattach the retaining clips and reconnect the injector connector.

4. Conduct Compression Test (if misfire persists)

• Sub-steps:
  1. Remove the spark plug from cylinder 1 (if not already done).
  2. Insert the compression gauge into the spark plug hole.
  3. Crank the engine for a few seconds and record the compression reading.
  4. Compare the reading to specifications (typically around 180 psi for most engines).

Tools Required:

• OBD-II scanner
• Socket set
• Spark plug socket
• Compression tester
• Multimeter
• Torque wrench

Parts Required:

• Spark plug (specific to vehicle model)
• Ignition coil (for cylinder 1)
• Fuel injector (if found faulty)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before removing any components to prevent burns.