how to fix the P0301 misfire code on my 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 needed.
• Disconnect the battery to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the intake cover if necessary to access cylinder one.
• Disconnect the ignition coil connector.
• Remove the ignition coil and spark plug.
• Inspect the spark plug for fouling or damage; replace if necessary.
• Install a new spark plug to the manufacturer's torque specification (typically around 15-20 ft-lbs).

3. Check and Replace Ignition Coil

• Tools Required: Socket set.
• Inspect the ignition coil for cracks or damage.
• If faulty, remove the ignition coil from the cylinder one position.
• Install a new ignition coil ensuring it is securely seated and connected.

4. Test Fuel Injector

• Tools Required: Noid light or multimeter.
• Disconnect the fuel injector connector for cylinder one.
• Use a noid light to check for signal; if no light, the injector is faulty.
• Replace the injector if it fails the test by removing the fuel rail and installing a new injector.

5. Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder one.
• Insert the compression tester and crank the engine.
• Compare the reading to manufacturer specifications (typically 120-180 psi).
• If readings are low, investigate further for potential internal engine issues.

6. Final Assembly

• Reconnect all components that were removed.
• Reconnect the battery.
• Clear the error codes using an OBD-II scanner.