what does it mean if my Toyota Highlander has a P0303 misfire code

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Remove the spark plug wire or coil pack from cylinder 3.
• Use a socket wrench to remove the spark plug.
• Inspect the spark plug for wear or fouling; replace it if necessary.
• Torque the new spark plug to manufacturer specifications (typically 13-15 lb-ft for most Toyota models).
• Reattach the spark plug wire or coil pack securely.

3. Inspect and Replace Ignition Coil

• Remove the ignition coil from cylinder 3 by unscrewing the bolts and disconnecting the electrical connector.
• Inspect the ignition coil for signs of damage or burn marks.
• Install the new ignition coil, ensuring to reconnect the electrical connector and torque the bolts to manufacturer specifications.

4. Test and Replace Fuel Injector (if needed)

• Remove the fuel injector connector from cylinder 3.
• Use a multimeter to test the resistance of the fuel injector to ensure it is within the specified range.
• If the injector is faulty, remove it from the fuel rail and replace it with a new one, ensuring proper sealing and connection.

5. Check Compression

• Remove the spark plug from cylinder 3.
• Insert a compression gauge into the spark plug hole.
• Crank the engine and read the compression value; it should meet manufacturer specifications (typically 150-200 psi).
• If compression is low, further inspection may be needed for valve or piston issues.