GMC Sierra T1XX (2019-Present) P0301 misfire code what does it mean

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, multimeter, compression tester, fuel pressure gauge, basic hand tools
• Safety Warnings: Disconnect the battery before working on electrical components.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Disconnect the ignition coil connector from cylinder 1.
• Remove the ignition coil bolt and carefully pull the coil out.
• Using a spark plug socket, remove the old spark plug from cylinder 1.
• Inspect the spark plug for wear; if it’s fouled or damaged, replace it with a new spark plug of the correct specification.
• Install the new spark plug, torque it to manufacturer specifications (typically around 15-20 lb-ft).
• Reinstall the ignition coil and reconnect the connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil showed signs of failure during inspection, replace it.
• Remove the ignition coil from cylinder 1 as described above.
• Install the new ignition coil, ensuring it is seated correctly, and torque the mounting bolt to the specified value (typically around 89-106 in-lbs).

4. Inspect and Clean Fuel Injector

• If the fuel injector is faulty, remove it from cylinder 1.
• Clean the injector using a specialized injector cleaner or replace it with a new injector.
• Reinstall the fuel injector, ensuring O-rings are properly seated to prevent leaks.

5. Recheck Compression (if needed)

• If compression was low, consider further diagnostics or repairs (e.g., valve issues, head gasket failure).
• If compression is normal, proceed to the next steps.