2016 GMC Sierra 1500 Spark Plug Type, Gap & Torque Specs

As an ASE-certified master technician, I’ve pulled hundreds of spark plugs out of GM's EcoTec3 engines. If your 2016 GMC Sierra 1500 is approaching the 100,000-mile mark, or if you're experiencing a rough idle, misfires, or a drop in fuel economy, it's time to talk about spark plugs. The 2016 Sierra 1500 relies on a coil-near-plug ignition system, and keeping those spark plugs firing optimally is critical to the performance of its direct-injected powerplants.

Here is the exact information you need to get the job done right on your 4.3L V6, 5.3L V8, or 6.2L V8.

Quick reference

Why the right plug matters

Modern engines like the Gen V EcoTec3 family used in the 2016 Sierra 1500 are incredibly sensitive to spark plug design. You cannot simply throw cheap copper plugs into these engines.

The OEM ACDelco 41-114 plugs are iridium. Iridium is significantly harder and more durable than platinum or copper, allowing the center electrode to be wire-fine. This fine tip requires less voltage to jump the gap, creating a highly efficient spark that optimizes combustion in these high-compression, direct-injected engines. Heat range is equally critical. Using a plug with the wrong heat range can lead to pre-ignition (if it's too hot) or carbon fouling (if it's too cold). Stick with the exact OEM ACDelco Iridium or a premium equivalent like NGK Iridium IX to ensure the heat range perfectly matches the factory calibration.

How to gap a spark plug

Most premium iridium plugs, including the ACDelco 41-114, come pre-gapped from the factory at 0.040 inches. However, plugs can easily be dropped or bumped during shipping. Always verify the gap before installation.

To check the gap, use a wire-style gap gauge or a feeler gauge—avoid the cheap "coin-style" gauges, as they can easily snap the delicate iridium tip. Carefully slide the 0.040" wire between the center and ground electrode; there should be a slight drag. If the gap is too tight, use the adjustment tool on your gauge to apply a light bend to the ground electrode only. Never pry against the fragile iridium center electrode.

Replacement procedure tips

Replacing plugs on the 2016 Sierra 1500 is relatively straightforward thanks to the coil-near-plug design (often conflated with coil-on-plug, but GM uses a short ignition wire between the coil and plug).

1. Accessing the plugs: The passenger side rear plugs can be a bit tight near the firewall, so a flex-head ratchet and various extensions will be your best friend.
2. The anti-seize debate: GM specifically advises against using anti-seize on the spark plug threads. The ACDelco plugs feature a special zinc/nickel coating that prevents them from seizing in the aluminum cylinder heads. Adding anti-seize acts as a lubricant, which often leads to over-torquing and stripping the delicate aluminum threads. Install them completely dry.
3. Dielectric grease: Apply a small pea-sized dab of dielectric grease to the inside of the spark plug boot before reattaching it. This prevents the rubber from sticking to the porcelain insulator next time and helps keep moisture out.
4. Torque matters: Always use a torque wrench and tighten the plugs to the factory spec of 11 lb-ft (15 Nm).

Known issues

While the 2016 Sierra doesn't suffer from the notorious broken-in-the-head two-piece spark plug issues that plagued early 2000s Ford 3-valve engines, there is a quirk to watch out for. GM uses the spark plugs as part of the engine’s misfire and knock detection via ionization sensing in the ignition coils. Because of this, using counterfeit plugs or standard copper/platinum plugs will frequently trigger phantom P0300 (Random/Multiple Cylinder Misfire) codes.

Additionally, the factory spark plug wires on these trucks are notorious for their heat shields seizing to the spark plug bodies. Do not pull on the wire itself. Twist the metal heat shield at the base of the boot back and forth to break the seal before pulling. If you rip a wire, you'll need a replacement set.

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