2019 GMC Yukon Spark Plug Type, Gap, and Torque Specs

As an ASE-certified master technician, I’ve pulled thousands of spark plugs from GM’s family of V8 engines. If you’re gearing up to do a tune-up on a 2019 GMC Yukon, you are dealing with GM’s Gen V direct-injected EcoTec3 powerplants—specifically the 5.3L (L83) or the 6.2L (L86) V8. Both are fantastic engines, but they require precision when it comes to ignition maintenance.

Below is everything you need to know about spark plug part numbers, gaps, torque specs, and replacement procedures for your 2019 Yukon.

Quick reference

(Note: GM occasionally updates part numbers. ACDelco 41-114 is the standard OEM iridium replacement. Always verify your specific VIN when purchasing.)

Why the right plug matters

Modern engines are incredibly sensitive to spark plug design. You cannot simply throw a cheap copper plug into a 2019 Yukon and expect it to run correctly. The GM Gen V V8s require an iridium electrode.

Iridium is highly resistant to wear, which allows for the 100,000-mile service interval. More importantly, these engines utilize Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) cylinder deactivation, alongside direct injection. The exact heat range of the OEM ACDelco or equivalent NGK plug ensures complete combustion, preventing soot buildup and maintaining the correct ionization sensing signals the ECM uses to detect misfires. Dropping down to platinum or copper will result in premature wear, poor fuel economy, and likely a check engine light.

How to gap a spark plug

Most premium iridium spark plugs, including the ACDelco 41-114, come pre-gapped from the factory at 0.040". However, it is always a best practice to verify the gap before installation in case the box was dropped during shipping.

1. Use a wire-style gauge: Do not use a cheap coin-style gauge on iridium plugs. The center electrode is extremely fine and brittle; a coin gauge can easily snap it off.
2. Check gently: Slide the 0.040" (1.0 mm) wire through the gap. It should pass through with a slight drag.
3. Adjusting the gap: If the gap is too tight or too loose, use the bending tool on your gauge to carefully bend the ground strap. Never pry against the center iridium tip!

Replacement procedure tips

The 2019 GMC Yukon uses a "coil-near-plug" ignition system. Instead of the coil sitting directly on top of the plug, it sits on the valve cover with a short spark plug wire connecting the two.

• Wire removal: These wires have metal heat shields. Twist the boot slightly to break the seal before pulling. Do not yank the wire itself, or you will pull the terminal right off the core.
• The anti-seize debate: GM specifies installing these plugs dry. ACDelco and premium NGK plugs feature a special trivalent metal plating that acts as a release agent. Adding anti-seize can act as a lubricant, causing you to over-torque the plug and damage the aluminum cylinder head threads.
• Dielectric grease: Apply a small pea-sized amount of dielectric grease to the inside of the spark plug wire boots before reinstalling. This prevents moisture intrusion and stops the rubber from baking onto the plug's porcelain over the next 100,000 miles.
• The dreaded #8 cylinder: The passenger-side rear plug (cylinder 8) is notoriously tight against the firewall/HVAC box. Use a combination of a short spark plug socket, a universal joint (wobble socket), and a short extension to get it out without unbolting the engine mounts.

Known issues

While you won't encounter the infamous Ford 3-valve two-piece spark plug breakage on a GMC, the 5.3L and 6.2L engines have their own quirks. Because these are direct-injected engines, they produce more soot than older port-injected V8s. If you remove the plugs and notice heavy, dry black soot, the engine may be experiencing early signs of carbon buildup on the intake valves or running slightly rich.

Additionally, engines that consume oil due to AFM lifter issues or PCV ingestion may severely foul the spark plugs on cylinders 1, 4, 6, and 7 (the deactivation cylinders). If you pull a plug that is completely caked in thick, oily ash, you likely have an internal oil consumption issue that needs addressing beyond a simple tune-up.

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