how to diagnose P0301 code in my Toyota Corolla E210 (2019-2024)?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the engine is cool, and disconnect the battery to prevent electrical shock.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester.

2. Inspect and Replace Spark Plug

• Locate the spark plug for cylinder 1 (usually the front left, facing the engine).
• Remove the ignition coil by unscrewing it and gently pulling it out.
• Disconnect the electrical connector from the ignition coil.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear or carbon buildup; replace it if necessary.
• Install a new spark plug with the proper gap (usually around 0.043 inches for most models).
• Torque the spark plug to the manufacturer’s specification (typically 13-16 lb-ft).

3. Check and Replace Ignition Coil

• If the spark plug is fine, test the ignition coil for proper resistance using a multimeter.
• If it is out of specification, replace the ignition coil with a new one.
• Reinstall the ignition coil on the spark plug and reconnect the electrical connector.

4. Inspect Fuel Injector

• If misfire persists, check the fuel injector for cylinder 1.
• Disconnect the fuel injector connector and test the resistance with a multimeter.
• If the resistance is not within the specified range (usually 12-16 ohms), replace the fuel injector.
• Ensure the injector seals are intact and reinstall it.

5. Conduct Compression Test

• If all components are functioning correctly, perform a compression test on cylinder 1.
• Remove the spark plug and insert the compression tester into the spark plug hole.
• Crank the engine a few times and record the reading.
• Compare the compression reading to the manufacturer's specifications; low compression may indicate internal engine issues.