how to diagnose P0302 misfire code in my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on it.

2. Inspect and Replace Ignition Components

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Remove the engine cover (if applicable) using a socket set.
• Unscrew and remove the ignition coil from cylinder 2.
  • Torque value for reinstallation: 7 ft-lbs (9.5 Nm).
• Inspect the ignition coil for cracks or signs of wear.
• Remove the spark plug from cylinder 2 using a spark plug socket.
• Inspect the spark plug for wear, carbon buildup, or damage. Replace if necessary.
• Apply dielectric grease to the ignition coil boot before reinstallation.
• Reinstall the spark plug and ignition coil, ensuring they are securely fastened.

3. Inspect and Replace Fuel Injector

• Tools Required: Fuel injector puller (if necessary), cleaning supplies.
• Disconnect the fuel injector connector for cylinder 2.
• Remove the fuel rail bolts and carefully pull the fuel rail away to access the injector.
• Remove the fuel injector from the fuel rail.
• Inspect the injector for clogs and perform cleaning or replacement as needed.
• Reassemble the fuel rail and reconnect the fuel injector connector.

4. Check for Vacuum Leaks

• Visually inspect all vacuum lines for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to help identify leaks.
• Replace any damaged vacuum lines as necessary.

5. Perform Compression Test

• Tools Required: Compression gauge.
• Remove all spark plugs to allow for accurate readings.
• Insert the compression gauge into the spark plug hole for cylinder 2.
• Crank the engine and record the compression reading.
• Compare the reading to manufacturer specifications; if low, further diagnosis is needed for mechanical issues.