how to diagnose P0301 code on 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 during repairs.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the engine cover if necessary to access the spark plug.
• Use a socket wrench to remove the spark plug from cylinder 1.
• Inspect the spark plug for signs of fouling or wear; replace if necessary.
• Install a new spark plug and torque it to the manufacturer’s specifications (typically 15 lb-ft).
• Reinstall the engine cover if removed.

3. Check and Replace Ignition Coil

• Tools Required: Socket set
• Disconnect the electrical connector from the ignition coil on cylinder 1.
• Remove the ignition coil by unscrewing it from the cylinder head.
• Inspect the coil for cracks or signs of failure; replace if faulty.
• Install the new ignition coil and reconnect the electrical connector.

4. Test and Replace Fuel Injector

• Tools Required: Fuel injector tester or noid light
• Disconnect the fuel injector connector from cylinder 1.
• Use a noid light to ensure the injector is receiving the proper electrical signal.
• If the signal is present but the injector is not functioning, remove the injector and clean or replace it.
• Reinstall the injector and reconnect the electrical connector.

5. Perform Compression Test

• Tools Required: Compression tester
• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine several times to obtain a compression reading.
• Compare the reading to specifications; if low, further engine diagnostics may be necessary.