how to fix P0303 code in my Toyota Highlander XU70 (2020-Present)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shock.
• Allow the engine to cool down before proceeding.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 3:
  • Use a socket set to unbolt the coil.
  • Gently pull the coil off the spark plug.
• Remove the spark plug:
  • Use a spark plug socket and ratchet to unscrew the spark plug.
  • Inspect the spark plug for wear or fouling.
• Install a new spark plug:
  • Gap the new spark plug to the manufacturer specifications (typically 0.044 inches for Toyota).
  • Torque the spark plug to the specified value (usually around 13-15 ft-lbs).
• Reinstall the ignition coil.

3. Check and Replace Ignition Coil

• If the spark plug appears fine, test the ignition coil:
  • Use a multimeter to check the primary and secondary resistance of the ignition coil.
  • If the coil is faulty, replace it with a new one.
• Reconnect the ignition coil and ensure all connections are secure.

4. Fuel Injector Inspection

• Disconnect the fuel injector connector for cylinder 3.
• Test the injector:
  • Use a noid light to check for signal or test the resistance across the injector terminals.
• If the injector is faulty, replace it with a new one.

5. Reassemble and Reconnect

• Reconnect all wiring harnesses and ensure everything is properly seated.
• Reconnect the battery.