how to fix P0301 code on GMC Sierra T1XX (2019-Present)?

Learn how to diagnose and fix P0301 cylinder 1 misfire in GMC Sierra T1XX. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Remove the ignition coil from cylinder 1 by unscrewing the bolts and disconnecting the electrical connector.
• Remove the spark plug using the spark plug socket. Inspect it for wear or damage (e.g., carbon buildup, cracked insulator).
• If necessary, replace the spark plug with a new one (consult manufacturer specifications for part number).
• Apply a small amount of dielectric grease to the spark plug threads to prevent seizing.
• Reinstall the spark plug and torque to manufacturer specifications (typically around 15-20 ft-lbs).

3. Check and Replace Ignition Coil

• Tools Required: Socket set, torque wrench.
• Inspect the ignition coil for signs of damage or corrosion.
• If the ignition coil shows signs of wear, replace it with a new coil specific for cylinder 1.
• Reinstall the ignition coil, ensuring it clicks into place and secure it with bolts.
• Reconnect the electrical connector.

4. Test Fuel Injector

• Tools Required: Noid light or multimeter.
• Disconnect the fuel injector connector for cylinder 1.
• Use a noid light to check for proper signal; if it does not flash, check the wiring and ECM.
• If the injector is faulty, remove it and replace it with a new fuel injector.
• Reconnect the fuel injector and its electrical connector.

5. Reassemble and Clear Codes

• Reconnect the negative battery terminal.
• Start the engine and allow it to idle. Check for any abnormal sounds or vibrations.
• Use the OBD-II scanner to clear the P0301 code and verify that it does not reappear after a test drive.