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

Solution

1. Preparation

• Gather tools and parts for the repair.
• Disconnect the battery to ensure safety during the repair.
• Tools Required: OBD-II scanner, socket set, torque wrench, spark plug socket, compression tester, fuel injector cleaner.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1.
  • Tools: Socket set, torque wrench.
  • Safety Warning: Ensure the battery is disconnected before starting.
• Remove the spark plug using the spark plug socket.
• Inspect the spark plug for fouling, wear, or damage. Replace if necessary.
• Install a new spark plug, ensuring it is gapped according to specifications (typically around 0.043 inches for this model).
• Reinstall the ignition coil and connect the wiring harness.

3. Test and Replace Ignition Coil

• If the spark plug appears normal, test the ignition coil using a multimeter.
  • Measure the primary and secondary resistance according to manufacturer specifications.
• If the ignition coil is faulty, replace it with a new one.
• Reconnect the ignition coil to the spark plug.

4. Compression Test

• Perform a compression test on cylinder 1 to check for internal engine issues.
  • Remove the spark plug and connect the compression tester.
  • Crank the engine and record the compression reading; it should be within the manufacturer’s specified range.
• If compression is low, further investigation into internal engine components is needed.

5. Fuel Injector Inspection

• Remove the fuel injector for cylinder 1.
  • Tools: Socket set, fuel line disconnect tool.
• Inspect the injector for clogs or damage. Clean or replace as necessary.
• Reinstall the fuel injector and ensure proper connection.