GMC Sierra T1XX (2019-Present) engine light on with code P0301, what should I do?

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 ensure safety.

2. Inspect and Replace Ignition Components

• Inspect Spark Plug:

  • Remove the spark plug from cylinder 1 using a spark plug socket.
  • Check for signs of wear, carbon buildup, or damage.
  • Replace with a new spark plug if necessary (use OEM specifications).

• Inspect Ignition Coil:

  • Remove the ignition coil from cylinder 1.
  • Check for any cracks or signs of failure.
  • Replace with a new ignition coil if necessary.

3. Check and Clean Fuel Injector

• Remove Fuel Injector:

  • Disconnect the electrical connector and fuel line from the injector.
  • Remove the fuel injector using a socket or wrench.

• Clean or Replace:

  • Clean the injector using a specialized fuel injector cleaner or replace with a new injector if clogged or defective.

4. Perform Compression Test

• Set Up Compression Tester:

  • Remove the spark plug from cylinder 1.
  • Insert the compression tester into the spark plug hole.

• Conduct Test:

  • Crank the engine and record the compression reading.
  • Compare it to the manufacturer's specifications. If it's low, further investigation is needed into engine internals.

5. Reassemble and Reconnect

• Reinstall the fuel injector, ignition coil, and spark plug.
• Reconnect any electrical connectors and fuel lines.
• Reconnect the negative battery terminal.