how to fix P0301 misfire code in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface and the ignition is off.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Gather tools and parts required for the repair.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Sub-steps:
  1. Locate the spark plug for cylinder 1 (typically the front left when facing the engine).
  2. Remove the ignition coil by unscrewing it and gently pulling it out.
  3. Use the spark plug socket to remove the old spark plug.
  4. Inspect the new spark plug for proper gap size according to manufacturer specifications (typically 0.043 inches).
  5. Install the new spark plug and torque it to the manufacturer's specification (usually around 13-16 lb-ft).
  6. Reinstall the ignition coil.

3. Inspect and Replace Ignition Coil

• Tools Required: Socket set, torque wrench.
• Sub-steps:
  1. If the spark plug replacement did not resolve the issue, remove the ignition coil from cylinder 1.
  2. Use a multimeter to test the coil’s primary and secondary resistance (refer to manufacturer specifications).
  3. Replace the ignition coil if it fails the test or shows signs of wear.
  4. Reinstall the ignition coil and secure it properly.

4. Test Fuel Injector

• Tools Required: Fuel injector tester or multimeter.
• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 1.
  2. Use a multimeter to check for continuity and resistance in the injector (refer to specifications).
  3. If the injector is faulty, remove it and replace it with a new one.
  4. Reconnect the fuel injector harness.

5. Perform Compression Test

• Tools Required: Compression tester.
• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine several times to record the pressure reading.
  4. Compare the reading to manufacturer specifications; if low, further diagnosis may be needed.