how to resolve the P0301 misfire code on my 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 all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Replace Spark Plug and Ignition Coil

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Remove the engine cover if applicable.
• Disconnect the ignition coil connector from the ignition coil.
• Remove the ignition coil mounting bolts and remove the coil.
• Unscrew the spark plug using a spark plug socket.
• Inspect the old spark plug for wear; if it’s fouled or damaged, replace it.
• Install the new spark plug, torquing it to the manufacturer’s specifications (typically around 15-20 lb-ft).
• Apply dielectric grease to the ignition coil boot and reinstall the ignition coil.
• Reconnect the ignition coil connector.

3. Test Fuel Injector

• Tools Required: Noid light or multimeter.
• Disconnect the fuel injector connector for cylinder 1.
• Connect a noid light to the injector connector to check for pulse during cranking.
• If no pulse is detected, check the wiring and connectors for continuity.
• If the injector is faulty, replace it by removing the fuel rail (follow safety procedures for fuel systems).

4. Perform Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1.
• Screw the compression tester into the spark plug hole.
• Crank the engine for a few seconds and record the compression reading.
• Compare the reading to manufacturer specifications (usually around 120-190 psi). If low, investigate further for potential internal issues.