how to diagnose and fix the P0301 code in my Toyota RAV4 Fourth Generation?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, compression tester, fuel injector cleaner.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1 using a socket set.
• Unscrew the spark plug and inspect it for signs of wear, carbon buildup, or damage.
• If necessary, replace the spark plug with a new one (typically NGK or Denso).
• Torque the new spark plug to the manufacturer’s specification (usually around 13 lb-ft or 18 Nm).

3. Test and Replace Ignition Coil

• Using a multimeter, test the resistance of the ignition coil for cylinder 1.
• If the resistance is outside the specified range, replace the ignition coil.
• Install the new ignition coil and ensure it is seated properly.

4. Compression Test

• Remove the spark plug from cylinder 1 and insert the compression tester.
• Crank the engine and record the compression reading.
• Compare the reading to the manufacturer’s specifications. If low, further inspection of valve seals or piston rings may be needed.

5. Fuel Injector Inspection

• Use a fuel injector cleaner to clean the injector for cylinder 1.
• If cleaning does not resolve the issue, consider replacing the fuel injector.
• Ensure the new injector is installed securely and properly connected.