what does the code P0303 indicate for my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to avoid electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug from cylinder 3.
• Inspect the spark plug for wear or damage; replace if necessary.
• Gap the new spark plug to the manufacturer’s specification (typically around 0.043 inches for Toyota).
• Install the new spark plug and torque it to the manufacturer’s specification (usually 13 ft-lbs).

3. Check and Replace Ignition Coil

• Disconnect the electrical connector from the ignition coil on cylinder 3.
• Remove the ignition coil by unscrewing the bolts.
• Inspect the coil for damage; replace if necessary.
• Install the new ignition coil and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Disconnect the fuel injector connector for cylinder 3.
• Remove the fuel injector using appropriate tools (may require a fuel line removal tool).
• Inspect the injector for clogs; clean or replace as needed.
• Reinstall the injector and reconnect the connector.

5. Perform Compression Test (if necessary)

• Remove the spark plug from cylinder 3.
• Insert a compression gauge into the spark plug hole.
• Crank the engine and observe the compression reading; compare it to the manufacturer's specifications (approximately 180-200 psi).
• If low, further investigation for mechanical issues may be required.