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

Solution

1. Preparation

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

2. Replace Spark Plug

• Remove the ignition coil from cylinder 3 by unscrewing the retaining bolts.
• Disconnect the electrical connector from the ignition coil.
• Remove the old spark plug using a socket wrench.
• Install a new spark plug, ensuring it is gapped correctly (typically around 0.044 inches for most Toyota engines).
• Reattach the ignition coil and secure it with bolts.

3. Inspect and Replace Ignition Coil (if necessary)

• If the spark plug replacement does not resolve the issue, test the ignition coil with a multimeter for resistance.
• If the coil is faulty, replace it with a new one.
• Reinstall the ignition coil on cylinder 3, ensuring proper connection and securing it with bolts.

4. Clean or Replace Fuel Injector

• Remove the fuel rail to access the injector for cylinder 3.
• Inspect the injector for clogs or leaks.
• Clean the injector with a specialized cleaner or replace it if necessary.
• Reinstall the fuel rail, ensuring all seals are properly seated.

5. Compression Test (if misfire persists)

• Perform a compression test on cylinder 3 using a compression gauge.
• Ensure the readings are within the manufacturer's specifications (typically around 180-210 psi).
• If compression is low, further diagnostics may be needed for potential internal engine issues.