how to diagnose P0301 code on my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, torque wrench, compression tester, multimeter.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace Spark Plug

1. Remove the ignition coil by unscrewing the mounting bolts and disconnecting the electrical connector.
2. Extract the spark plug using a spark plug socket.
3. Inspect the spark plug for wear or fouling. Replace if necessary.
4. Install the new spark plug (use OEM recommended gap) and torque to 13 lb-ft.
5. Reattach the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil

1. If the spark plug is in good condition, test the ignition coil using a multimeter for resistance.
2. If out of spec, replace the ignition coil with a new one.
3. Reinstall the coil, ensuring it is securely connected to the spark plug.

4. Test Fuel Injector

1. Disconnect the fuel injector connector for cylinder 1.
2. Use a multimeter to check the resistance of the injector; it should be within the manufacturer's specifications.
3. If faulty, replace the fuel injector with a new one.
4. Reconnect the injector and ensure it is seated properly.

5. Perform Compression Test

1. Remove the spark plug from cylinder 1.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine and record the compression reading for cylinder 1.
4. Compare the reading to manufacturer specifications; if low, further investigation into engine internals may be required.