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 tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shocks.
• Allow the engine to cool down before starting work.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug wire or ignition coil from cylinder 1.
• Use a spark plug socket to remove the old spark plug from cylinder 1.
• Inspect the spark plug for signs of fouling or damage.
• Install a new spark plug (gapping it according to manufacturer specifications).
• Torque the new spark plug to the manufacturer's recommended value (typically around 15 lb-ft).

3. Inspect and Replace Ignition Coil

• Remove the ignition coil for cylinder 1 by unscrewing the bolts.
• Disconnect the electrical connector from the ignition coil.
• Compare the old ignition coil with the new one to ensure compatibility.
• Install the new ignition coil and reconnect the electrical connector.
• Secure the ignition coil with the bolts and torque them to the specified value.

4. Check Fuel Injector

• Disconnect the fuel injector connector for cylinder 1.
• Remove the fuel rail if necessary to access the injector.
• Inspect the fuel injector for clogs or leaks; clean or replace as needed.
• Reinstall the fuel injector and ensure it is seated properly in the rail.
• Reattach the fuel rail and reconnect the fuel injector connector.

5. Compression Test (if necessary)

• Remove the spark plug from cylinder 1.
• Insert a compression gauge into the spark plug hole.
• Crank the engine a few times to get a reading; compare this with manufacturer specifications.
• If the compression is low, further engine diagnostics may be required.