how to fix P0301 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: OBD-II scanner, multimeter, spark plug socket, torque wrench, compression tester, replacement spark plug, ignition coil (if needed).
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Remove the engine cover if necessary.
• Locate cylinder 1 spark plug (front driver’s side).
• Use a spark plug socket to remove the spark plug.
• Inspect the spark plug for wear or deposits; replace with a new spark plug if it shows signs of damage.
• Torque the new spark plug to the manufacturer's specifications (typically around 15 lb-ft).

3. Test and Replace Ignition Coil

• Disconnect the ignition coil connector from cylinder 1.
• Use a multimeter to measure the resistance of the ignition coil; compare with specifications (typically 0.5 to 1.5 ohms).
• If defective, remove the ignition coil using a socket and replace it with a new one.
• Reconnect the ignition coil connector and ensure it is seated properly.

4. Check Fuel Injector

• Disconnect the fuel injector connector for cylinder 1.
• Use a noid light to check for injector signal; if no signal, further diagnosis may be required for wiring or ECU issues.
• If the injector is faulty, remove it and replace it with a new one, ensuring proper sealing during installation.

5. Verify and Reassemble

• Reconnect all components and the battery.
• Clear the error codes from the OBD-II scanner.
• Start the engine and let it idle; monitor for smooth operation and check if the check engine light remains off.