how to fix P0302 misfire code on Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down completely.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench, dielectric grease.
• Remove the engine cover if applicable.
• Disconnect the ignition coil connector for cylinder 2.
• Remove the ignition coil by unbolting it.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear or fouling; replace if necessary.
• Install the new spark plug, ensuring it is torqued to the manufacturer's specifications (typically around 13-16 lb-ft).
• Apply a small amount of dielectric grease to the ignition coil boot and reinstall the ignition coil.

3. Inspect and Replace Fuel Injector

• Tools Required: Fuel injector removal tool, ratchet set, O-ring lubricant.
• Locate the fuel rail and disconnect the fuel line using a proper tool to relieve pressure.
• Remove the retaining clips and detach the fuel injector from the rail.
• Inspect the injector for clogs or leaks; replace if faulty.
• Lubricate the new injector O-rings with engine oil and install it into the rail.
• Reattach the fuel line and ensure all connections are secure.

4. Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 2.
• Insert the compression tester into the spark plug hole.
• Crank the engine for several revolutions and record the pressure reading.
• Compare it to specifications (around 150 psi for most engines); if low, further diagnosis on valves or piston rings is required.

5. Vacuum Leak Inspection

• Tools Required: Smoke machine or carburetor cleaner.
• Perform a smoke test or spray carburetor cleaner around the intake manifold and vacuum hoses while the engine is running.
• Look for changes in idle speed that indicate a vacuum leak.
• Repair any detected leaks.