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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, vacuum gauge, multimeter.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Locate the spark plug for cylinder 1 (usually nearest to the front of the engine).
3. Use a socket wrench to remove the spark plug.
4. Inspect the spark plug for damage or fouling. Replace if necessary.
5. Ensure the new spark plug is gapped correctly according to manufacturer specifications (typically 0.044 inches).
6. Install the new spark plug and torque it to 13 lb-ft (17.6 Nm).

3. Inspect and Replace Ignition Coil

1. Locate the ignition coil for cylinder 1 (usually mounted on top of the spark plug).
2. Disconnect the electrical connector from the ignition coil.
3. Remove the bolt securing the ignition coil using a socket wrench.
4. Pull the ignition coil out carefully.
5. Inspect the ignition coil for damage or wear. Replace if necessary.
6. Install the new ignition coil and torque the bolt to manufacturer specifications (generally around 7.2 lb-ft or 10 Nm).

4. Check Fuel Injector

1. Locate the fuel injector for cylinder 1 (usually attached to the intake manifold).
2. Disconnect the electrical connector from the fuel injector.
3. Use a socket to remove the fuel injector from its rail.
4. Inspect the injector for clogs or damage; clean or replace as necessary.
5. Reinstall the fuel injector and reconnect the electrical connector.

5. Compression Test

1. Remove the spark plug for cylinder 1 again.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine several times to obtain a reading.
4. Compare the compression reading with manufacturer specifications (typically around 180-210 psi).
5. If compression is low, further diagnosis is needed for possible internal engine issues.

6. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0301 code from the system.
3. Start the engine to check for any reoccurrence of the misfire code.