how to fix P0301 misfire code in 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 necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the spark plug wire or ignition coil from cylinder 1.
• Use the spark plug socket to remove the spark plug.
• Inspect the spark plug for wear, carbon deposits, or damage. Replace if necessary.
• Install the new spark plug and torque to manufacturer specifications (typically 20-30 Nm).
• Reconnect the spark plug wire or ignition coil.

3. Test and Replace Ignition Coil (if necessary)

• Tools Required: Socket set, multimeter.
• Remove the ignition coil from cylinder 1.
• Test the coil's primary and secondary resistance with a multimeter (consult specifications).
• If the coil is defective, replace it with a new one.
• Reinstall the ignition coil and reconnect the wiring harness.

4. Inspect and Replace Fuel Injector (if necessary)

• Tools Required: Fuel injector puller, socket set.
• Disconnect the fuel injector connector.
• Remove the fuel rail if necessary to access the injector.
• Check the injector for clogs or electrical issues.
• Replace the fuel injector if found defective.
• Reassemble the fuel rail and reconnect all connectors.

5. Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine and record the compression reading.
• Compare the reading to manufacturer specifications. If low, further inspection of valves and piston rings may be needed.

6. Check for Vacuum Leaks

• Inspect all vacuum hoses and intake gaskets for cracks or disconnections.
• Use a smoke machine or spray soapy water to identify leaks.
• Repair any leaks found to ensure proper engine operation.