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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coil from cylinder 1:
  1. Disconnect the electrical connector.
  2. Remove the mounting bolts and lift the coil out.
• Remove the spark plug:
  1. Use the spark plug socket to unscrew the spark plug.
  2. Inspect the old spark plug for wear, carbon buildup, or oil fouling.
• Install the new spark plug:
  1. Hand-tighten the new spark plug into the cylinder head.
  2. Use the torque wrench to tighten to the manufacturer's specification (typically around 13-16 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• Tools Required: Ratchet, socket set.
• Remove the faulty ignition coil (follow the steps in the previous section).
• Install the new ignition coil:
  1. Position the new coil in place.
  2. Secure it with the mounting bolts and reconnect the electrical connector.

4. Clean or Replace Fuel Injector (if necessary)

• Tools Required: Fuel injector removal tool, cleaning kit or replacement injector.
• Disconnect the fuel line (be cautious of fuel spills).
• Remove the fuel injector using the removal tool.
• Clean the injector using a cleaning kit or replace it with a new one.
• Reinstall the fuel injector, ensuring proper seating and sealing.

5. Perform Compression Test (if necessary)

• Tools Required: Compression gauge.
• Remove the spark plug from cylinder 1 and insert the compression gauge.
• Crank the engine and record the compression reading.
• Compare the reading to manufacturer specifications (typically 120-180 psi). If low, further investigation of engine internals may be necessary.