what causes a P0302 code on GMC Sierra T1XX (2019-Present)

Learn how to diagnose and fix P0302 cylinder 2 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 ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 2 by unbolting it and disconnecting the electrical connector.
  2. Extract the spark plug using a spark plug socket.
  3. Inspect the spark plug for wear, fouling, or damage. Replace if necessary.
  4. Gap the new spark plug to the manufacturer's specifications (typically around 0.030 - 0.035 inches).
  5. Install the new spark plug and torque to the specified value (usually around 15 lb-ft).

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is in good condition, test the ignition coil with a multimeter for primary and secondary resistance.
  2. If faulty, remove the ignition coil and replace it with a new one.
  3. Reinstall the ignition coil, ensuring it is properly seated and the electrical connector is secure.

4. Check and Replace Fuel Injector

• Sub-steps:
  1. Remove the fuel injector connector and inspect for any damage.
  2. Use a noid light to check for injector signal while cranking the engine.
  3. If the signal is present but the injector is not functioning, remove the fuel rail and replace the injector.
  4. Install the new fuel injector and reconnect the fuel rail and electrical connector.

5. Reassemble and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Start the engine and observe for any misfire symptoms or check engine light illumination.
  3. Clear the P0302 code using the OBD-II scanner and take the vehicle for a test drive.