how to fix P0303 misfire code in my Toyota RAV4 XA40 (2013-2018)

Solution

1. Preparation

• Gather the necessary tools and parts.
• Ensure the engine is cool and disconnect the negative battery terminal for safety.
• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, vacuum gauge.

2. Inspect and Replace Spark Plug

• Remove the ignition coil for cylinder 3:
  • Unplug the electrical connector.
  • Remove the mounting bolts using a socket.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for fouling or damage. Replace if necessary.
  • Torque the new spark plug to the manufacturer's specifications (typically around 13 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test and Replace Ignition Coil (if needed)

• Use a multimeter to test the resistance of the ignition coil:
  • Check primary and secondary resistance according to specifications (typically 0.4 to 0.6 ohms for primary).
  • Replace the ignition coil if readings are outside the specified range.
• Reinstall the ignition coil if it passes the test.

4. Compression Test

• Remove the spark plug from cylinder 3.
• Insert the compression tester into the spark plug hole and crank the engine.
• Record the maximum compression reading. It should typically be between 150-200 psi.
• Replace the cylinder head gasket or perform further repairs if compression is low.

5. Fuel Injector Inspection

• Remove the fuel rail to access the injector for cylinder 3:
  • Disconnect the fuel line (ensure proper fuel pressure relief).
  • Remove the fuel rail mounting bolts.
• Inspect the fuel injector for clogs or leaks. Clean or replace the injector as necessary.
• Reinstall the fuel rail, ensuring all seals are properly seated.