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

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaning kit.
• Gather necessary replacement parts (spark plug, ignition coil, fuel injector if needed).
• Disconnect the negative battery terminal to ensure safety.

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector from cylinder 1.
3. Remove the ignition coil using a socket set.
4. Use a spark plug socket to remove the old spark plug.
5. Inspect the spark plug gap and replace with a new spark plug if necessary, ensuring it is gapped according to manufacturer specifications.
6. Install the new spark plug and torque it to the manufacturer’s specification (typically around 11-15 lb-ft).
7. Reinstall the ignition coil and reconnect its connector.

3. Inspect and Replace Ignition Coil (if needed)

1. If the ignition coil was found faulty during diagnostics, proceed to replace it.
2. Remove the old ignition coil and install the new one, ensuring it is seated properly.
3. Reconnect the ignition coil connector.

4. Clean or Replace Fuel Injector (if needed)

1. If the fuel injector is clogged, use a fuel injector cleaning kit to clean it.
2. If it is defective, remove the fuel rail and replace the fuel injector for cylinder 1.
3. Reinstall the fuel rail and connect all necessary connectors.

5. Verify Compression (if needed)

1. If compression was low during testing, inspect the cylinder for potential issues such as a blown head gasket or valve problems.
2. Further repairs may be necessary based on findings.