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

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts and disconnecting the electrical connector.
• Remove the spark plug using the spark plug socket.
• Inspect the spark plug for fouling or wear, and replace it if necessary.
• Install a new spark plug and torque it to the manufacturer’s specification (typically around 13-16 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

• If the spark plug is in good condition but the misfire persists, test the ignition coil.
• Tools Required: Multimeter, socket set.
• Disconnect the ignition coil connector and remove the coil.
• Test the coil’s primary and secondary resistance using a multimeter; compare with manufacturer specifications.
• Replace the ignition coil if it is out of specification.
• Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

• Use a noid light to check the injector pulse for cylinder 1.
• If no pulse is detected, check the wiring and connectors leading to the injector.
• If the injector is faulty, remove it using a fuel injector puller.
• Install a new fuel injector and ensure it is seated correctly.

5. Compression Test (if necessary)

• If all previous checks are clear, perform a compression test on cylinder 1.
• Tools Required: Compression gauge.
• Remove the spark plug from cylinder 1 and insert the compression gauge.
• Crank the engine and note the pressure reading; compare it to manufacturer specifications.
• If compression is low, further engine diagnostics may be needed.