Engine-CodesGMC – P0302 2018 GMC Sierra

P0302 2018 GMC Sierra Code - Cylinder 2 Misfire Detected

Quick Answer

The P0302 code for a 2018 GMC Sierra indicates that there has been a misfire detected in cylinder 2 of the engine. Common causes include Faulty spark plug or ignition coil, Clogged fuel injector, Vacuum leak. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0302 2018 GMC Sierra indicates Cylinder 2 Misfire Detected.
Common causes
Common causes include Faulty spark plug or ignition coil, Clogged fuel injector, Vacuum leak.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Aug 30, 2024
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Code P0302 2018 GMC Sierra Description

The P0302 code for a 2018 GMC Sierra indicates that there has been a misfire detected in cylinder 2 of the engine. This means that the fuel-air mixture in that particular cylinder did not ignite properly, leading to a loss of power and potential damage to the engine if not addressed. The misfire can cause rough idling, a decrease in fuel efficiency, and overall poor performance of the vehicle. Ignoring this issue can lead to further damage to the catalytic converter, oxygen sensors, and spark plugs.

OBDII Code P0302 2018 GMC Sierra - Cylinder 2 Misfire Detected
P0302 2018 GMC Sierra Code - Cylinder 2 Misfire Detected

Common Causes of P0302 2018 GMC Sierra

  1. Faulty spark plug or ignition coil
  2. Clogged fuel injector
  3. Vacuum leak
  4. Low compression in cylinder 2
  5. Timing belt or chain issues

Symptoms of P0302 2018 GMC Sierra

  1. Engine misfiring or running rough
  2. Loss of power or acceleration
  3. Engine vibrations or shaking
  4. Check engine light illuminated
  5. Poor fuel economy

How to Fix P0302 2018 GMC Sierra

  1. Perform a thorough inspection of spark plugs, ignition coils, and fuel injectors in cylinder 2.
  2. Check for vacuum leaks and repair if necessary.
  3. Conduct a compression test to determine if there are any issues with cylinder 2.
  4. Inspect timing belt or chain for any signs of wear or misalignment.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0302 2018 GMC Sierra

The cost of repairing a cylinder 2 misfire in a 2018 GMC Sierra can vary depending on the cause of the issue. On average, the repair could range from $100 to $500, including parts and labor. However, this estimate may be higher if additional parts need to be replaced or if the underlying issue is more complex. It's recommended to consult with a trusted mechanic or auto repair shop to get a more accurate estimate based on the specific diagnosis and repair needed.

Tech Notes for P0302 2018 GMC Sierra

The P0302 code means that cylinder 2 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder 2. If the problem persists more tests need to be done to diagnose the problem, see "Possible Causes".

There is a Factory Service Bulletins for All 2000-2020 Chevrolet Models:
2000-2020 Chevrolet Factory Service Bulletin OBDII Code P0302
This Factory Service Bulletin explains how this condition may be caused by significant carbon build-up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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