my GMC Sierra T1XX (2019-Present) has a check engine light P0301, what does it mean?

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 necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if equipped.
  2. Disconnect the ignition coil connector from the cylinder 1 ignition coil.
  3. Remove the ignition coil by unscrewing the retaining bolts and pulling it out.
  4. Remove the spark plug using a spark plug socket and ratchet.
  5. Inspect the spark plug for wear or damage; replace if necessary with a new spark plug of the manufacturer's specifications (typically, a spark plug gap of 0.040 inches).
  6. Reinstall the new spark plug and torque it to the manufacturer's specifications (usually 15-20 lb-ft).
  7. Reinstall the ignition coil and reconnect the connector.

3. Test and Replace Fuel Injector (if necessary)

• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 1.
  2. Remove the fuel rail bolts and carefully lift the rail to access the injector.
  3. Inspect the fuel injector for clogs or damage and test its operation using a multimeter.
  4. If faulty, replace the fuel injector with a new one, ensuring proper seating and connection.
  5. Reinstall the fuel rail and reconnect all components.

4. Perform Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine several times and record the compression reading.
  4. Compare the reading to the manufacturer's specifications (typically 120-150 psi).
  5. If low, consider further diagnosing the engine for internal issues.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Spark plug socket
• Compression tester
• Multimeter
• Screwdrivers

Parts Required:

• Spark plug (if necessary)
• Fuel injector (if necessary)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow engine components to cool before handling.