how to fix misfire code P0301 on my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, replacement spark plug, ignition coil (if necessary), and fuel injector cleaner (if needed).
• Disconnect the battery to prevent electrical shorts.

2. Replace Spark Plug

1. Remove the engine cover (if applicable) using a socket set.
2. Locate the spark plug in cylinder 1.
3. Using a spark plug socket, carefully remove the old spark plug.
4. Inspect the spark plug for wear; check the gap and ensure it matches the manufacturer’s specifications (typically around 0.044 inches for Toyota).
5. Install the new spark plug by hand to avoid cross-threading, then tighten to the manufacturer’s torque specification (usually about 13-16 lb-ft).
6. Reconnect the ignition coil.

3. Inspect/Replace Ignition Coil

1. If the spark plug replacement did not resolve the issue, remove the ignition coil from cylinder 1.
2. Check the coil for cracks or signs of arcing. Use a multimeter to verify coil resistance (consult service manual for specific resistance values).
3. If defective, replace the ignition coil with a new one.
4. Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

1. If the ignition coil and spark plug are functioning properly, check the fuel injector for cylinder 1.
2. Disconnect the fuel injector connector and use a multimeter to measure voltage while cranking the engine.
3. If there is no voltage, inspect the wiring and connectors. If voltage is present but the injector is not firing, replace the fuel injector.
4. Clean the fuel injector if it appears clogged or replace it with a new one if necessary.