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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter.
• Disconnect the battery before working on electrical components to avoid shock or short circuits.

2. Inspect and Replace Spark Plug

• Remove the ignition coil for cylinder 1 by unscrewing the mounting bolts and unplugging the electrical connector.
• Remove the spark plug using a spark plug socket and inspect it for wear or fouling.
• If the spark plug is worn, replace it with a new one, ensuring it matches the manufacturer’s specifications (usually around 0.044 inches gap).
• Reinstall the spark plug, torque it to the manufacturer’s specification (typically around 13 ft-lbs).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test and Replace Ignition Coil

• If the spark plug is in good condition, test the ignition coil for cylinder 1 using a multimeter to check primary and secondary resistance.
• If the coil fails the test, replace it with a new OEM or equivalent part.
• Reconnect the ignition coil and ensure all connections are secure.

4. Inspect and Test Fuel Injector

• Remove the fuel injector for cylinder 1 by disconnecting the electrical connector and unscrewing the securing bolts.
• Test the fuel injector using a multimeter to check for resistance; if the readings are out of specification, replace the injector.
• Clean the injector if necessary or replace it with a new one, ensuring a proper seal upon reinstallation.

5. Perform Compression Test

• Remove the spark plug from cylinder 1 and install the compression tester.
• Crank the engine and record the compression reading. It should be within the manufacturer’s specified range (usually around 180-200 psi).
• If the compression is low, further investigation may be necessary to check for issues like a blown head gasket or worn piston rings.