my GMC Sierra T1XX (2019-Present) has a check engine light and code P0301

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 shocks.

2. Inspect and Replace Spark Plug

1. Remove the engine cover (if applicable) using a socket set.
2. Locate the spark plug for cylinder 1 (typically near the front of the engine).
3. Use a spark plug socket and ratchet to carefully remove the spark plug.
4. Inspect the spark plug for carbon buildup, oil fouling, or wear.
5. If necessary, replace the spark plug with a manufacturer-recommended part, ensuring the correct gap specification.
6. Reinstall the spark plug and torque it to the manufacturer's specification (usually around 13 lb-ft).

3. Inspect and Replace Ignition Coil

1. Disconnect the wiring harness from the ignition coil.
2. Remove the ignition coil mounting bolts using a socket set.
3. Inspect the ignition coil for signs of damage or corrosion.
4. If defective, replace with a new ignition coil compatible with the GMC Sierra.
5. Reinstall the ignition coil and reconnect the wiring harness.

4. Check and Replace Fuel Injector

1. Remove the intake manifold (if necessary) to access the fuel injector for cylinder 1.
2. Disconnect the fuel line (use caution and be prepared for fuel spillage).
3. Remove the fuel injector retaining clips and carefully pull the injector out.
4. Inspect the injector for clogs or damage; clean or replace as necessary.
5. Reinstall the new or cleaned injector ensuring proper seating and secure with clips.

5. Reassemble and Reconnect Battery

1. Reinstall any components removed during the repair (e.g., intake manifold, engine cover).
2. Reconnect the negative battery terminal.
3. Clear the trouble codes using the OBD-II scanner.