how to diagnose misfire on Toyota Corolla E210 (2019-2024) with P0301 code?

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, spark plug socket, torque wrench, cylinder compression tester, noid light.
• Disconnect the negative battery terminal for safety.
• Allow the engine to cool before proceeding.

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector for cylinder 1.
3. Remove the ignition coil using a socket set.
4. Unscrew and remove the spark plug using a spark plug socket.
5. Inspect the old spark plug for wear; check the gap using a feeler gauge.
6. Install the new spark plug, ensuring it is gapped correctly (typically around 0.043 inches for most Toyota applications).
7. Torque the spark plug to the manufacturer’s specification (usually around 13 lb-ft).

3. Inspect and Replace Ignition Coil (if necessary)

1. Test the ignition coil’s resistance with a multimeter; compare it to manufacturer specifications.
2. If outside of range, replace the ignition coil with a new one.
3. Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector (if necessary)

1. Disconnect the fuel injector connector for cylinder 1.
2. Use a noid light to check for injector pulse; replace the injector if there is no pulse.
3. If the injector is faulty, remove it and install the new injector, ensuring proper seating and connection.

5. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear any stored fault codes.