A Guide to Spark Plug Replacement for the 2015-2024 GMC Sierra 1500
Diagnose failing spark plugs and choose the right aftermarket replacements to keep your Sierra's engine running strong.
- Stick with Iridium plugs from ACDelco, NGK, or Denso for best performance and longevity.
- A persistent misfire (P0300 code) after changing plugs could be a sign of a known AFM lifter issue on 2015-2019 models.
- Replacement is DIY-friendly, but access to rear plugs is tight. For 2019+ models, removing the fender liners is the best approach.
- New plugs are pre-gapped; do not attempt to adjust them as you can easily damage the fine iridium tip.
Symptoms of Failing Spark Plugs
When your spark plugs are wearing out, your truck will give you several warning signs. Ignoring them can lead to poor performance and potentially damage other engine components.
- Rough Idle: Your truck may shake or vibrate more than usual when stopped at a light.
- Engine Misfires: You might feel a stutter, hesitation, or jerking sensation as you accelerate. This is often accompanied by a flashing check engine light.
- Reduced Power and Acceleration: Your Sierra may feel sluggish and slow to respond when you press the gas pedal.
- Worse Fuel Economy: Failing plugs burn fuel less efficiently, meaning you'll be stopping for gas more often.
- Trouble Starting: A weak spark can make it harder for the engine to turn over, especially in cold weather.
- Check Engine Light: A common code for spark plug issues is P0300 (random/multiple cylinder misfire) or codes P0301 through P0308, which point to a specific misfiring cylinder.
Vehicle-Specific Known Issues
AFM Lifter Issues (2015-2019 5.3L/6.2L): Technical Service Bulletin (TSB) 15-06-01-002I notes that a P0300 misfire code can sometimes be caused by a stuck or collapsed lifter in the Active Fuel Management (AFM) system, not a bad spark plug. If you replace your plugs and the misfire persists, this could be the underlying cause.
🎬 Watch: How to diagnose and replace a collapsed AFM lifter.Carbon Fouling from Short Trips: Modern direct-injection engines can be sensitive to frequent short drives where the engine doesn't fully warm up. This can cause carbon to build up on the spark plugs, leading to a rough idle or misfire. Often, a longer drive that allows the engine to reach operating temperature can clean the plugs and resolve the issue.
Choosing the Right Aftermarket Spark Plug
Your Sierra 1500 came from the factory with long-lasting iridium spark plugs. When choosing a replacement, it's best to stick with iridium plugs to maintain performance and the recommended service interval. Here’s a breakdown of available brands.
Brand Quality Tiers
- OEM-Equivalent (ACDelco): ACDelco is the original equipment manufacturer (OEM) for GM. Many owners and technicians recommend sticking with ACDelco plugs to avoid any compatibility issues. The current recommended part is often the 41-162, which superseded the older 41-110. You can't go wrong with the OEM choice.
- Premium Aftermarket (NGK, Denso): NGK and Denso are world-renowned Japanese brands that are often the actual manufacturers behind OEM plugs. Many professional mechanics consider them to be the highest quality aftermarket option, sometimes even exceeding OEM standards. Their Laser Iridium and Iridium TT lines are excellent choices for the Sierra.
- Standard Aftermarket (Bosch, Champion): These are well-known brands, but some users report issues like rough idling when using Bosch plugs in GM V8 engines. While they can be a cost-effective option, the general consensus in truck forums leans heavily toward ACDelco, NGK, or Denso for the best results.
- Budget (Skyward): This brand falls into the category of private label or store brands. While they are the most affordable, their long-term durability and performance may not match the premium brands. They can work in a pinch, but for a critical component like a spark plug, sticking with a proven manufacturer is a safer bet.
A Note on Spark Plug Wires
While you're replacing the spark plugs, it's a good idea to inspect the spark plug wires and boots. If they are original, consider replacing them at the same time. A damaged wire or boot can cause a misfire even with a brand new plug. Some users report that damaging a boot with pliers during removal is a common mistake.
Cost to Replace Spark Plugs on a 2015-2024 GMC Sierra 1500
| Category | Estimated Cost |
|---|---|
| Shop Labor | $210 - $310 |
| New OEM Plugs (8) | $125 - $150 |
| New Aftermarket Plugs (8) | $80 - $180 |
| Total Professional Replacement | $330 - $545 |
Frequently Asked Questions (FAQ)
When should I replace the spark plugs on my Sierra 1500?
The official recommendation for the original iridium plugs is typically around 100,000 miles. However, some service schedules suggest an inspection or replacement as early as 60,000 miles. If you are experiencing any failure symptoms, you should inspect them regardless of mileage.
Do I need to gap the new spark plugs?
Most modern iridium spark plugs, including the OEM ACDelco ones, come pre-gapped from the factory. It is generally recommended NOT to gap them yourself. The fine iridium tip is fragile and can be easily damaged by a gapping tool. Always verify you have the correct part number for your truck.
Should I use anti-seize on the spark plug threads?
This is a debated topic. Some plug manufacturers, like NGK, advise against it because their plugs have a special metal plating that prevents seizing and using anti-seize can cause you to over-torque the plug. ACDelco plugs for these trucks also come ready to install. If you do use it, use only a very small amount on the threads, avoiding the electrode.
Is it hard to change the spark plugs myself?
For a DIY mechanic, this job is manageable. On 2015-2018 models, access is primarily from the top of the engine bay. 🎬 Watch: Step-by-step spark plug and wire change for 2015-2018 models. For 2019+ models, the easiest way is to remove the front wheels and the fender liners to access the plugs from the side. 🎬 See this walkthrough for replacing plugs on 2019 and newer trucks. The rearmost cylinders (especially #8 on the passenger side) are the most difficult to reach.
Helpful Videos
Technical Specifications
OEM Part Numbers: ACDelco 41-162 ACDelco 41-110 GM 19417055
Material: Iridium, Socket Size: 5/8 inch, Torque Spec: ~11-15 ft-lbs
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- GMC Sierra 1500: