how to fix P0303 misfire code in my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Replace Ignition Coil

• Tools Required: Socket set, torque wrench, dielectric grease
• Remove the engine cover if applicable.
• Locate the ignition coil for cylinder 3.
• Unscrew the bolts securing the ignition coil and carefully disconnect the electrical connector.
• Remove the ignition coil and replace it with a new one.
• Apply dielectric grease to the connector and secure it back in place.
• Torque the bolts according to the manufacturer's specifications (usually around 80-100 in-lbs).

3. Replace Spark Plug

• Tools Required: Spark plug socket, torque wrench
• Remove the ignition coil if it is not already removed.
• Use a spark plug socket to remove the spark plug from cylinder 3.
• Inspect the old spark plug for wear; replace with a new spark plug if needed.
• Torque the new spark plug to the specified value (typically around 13-15 ft-lbs).
• Reinstall the ignition coil as described above.

4. Replace Fuel Injector (if necessary)

• Tools Required: Fuel line removal tool, torque wrench, new O-rings
• Depressurize the fuel system by removing the fuel pump fuse and starting the engine until it stalls.
• Disconnect the fuel line using a fuel line removal tool.
• Remove the bolts securing the fuel rail and lift it slightly to access the injector.
• Remove and replace the fuel injector for cylinder 3.
• Install new O-rings on the new injector and reassemble the fuel rail.
• Reconnect the fuel line and reinsert the fuel pump fuse.