2024 GMC Sierra 1500 Spark Plug Type & Gap Guide

Quick reference

Engine	OEM Plug PN (ACDelco)	Aftermarket (NGK/Denso)	Gap (in/mm)	Torque (lb-ft / Nm)	Interval (miles/km)
2.7L L3B Turbo	12698009	NGK R0ER6L11 / Denso ZT16TG	0.043 / 1.1	11 / 15	75,000 / 120,000
5.3L L84 V8	41-110	NGK LFR6AIX-11 / Denso Iridium Power IK20L	0.040 / 1.02	15 / 20	97,500 / 150,000
6.2L L87 V8	41-110	NGK LFR6AIX-11 / Denso Iridium Power IK20L	0.040 / 1.02	15 / 20	97,500 / 150,000

Note: Always verify the latest OEM and aftermarket part numbers with your vehicle's specific build and manufacturer recommendations.

Why the right plug matters

Choosing the correct spark plug for your 2024 GMC Sierra 1500 is critical for optimal engine performance, fuel efficiency, and longevity. Spark plugs are not "one size fits all" components; they are carefully engineered to meet the specific demands of each engine.

Heat range

The most important specification for a spark plug, after its physical dimensions, is its heat range. This refers to the plug's ability to dissipate heat from the combustion chamber. A "hotter" plug has a longer insulator nose and dissipates heat more slowly, while a "colder" plug has a shorter insulator nose and dissipates heat more quickly.

• Too hot: Can lead to pre-ignition (spark knock) and detonation, potentially damaging pistons and valves. The plug electrode can overheat and create a "hot spot."
• Too cold: Can cause carbon fouling, leading to misfires and poor performance. The plug electrode may not reach its self-cleaning temperature.

The engineers at GMC have carefully selected the ideal heat range for each engine in the Sierra 1500 to ensure efficient combustion and prevent engine damage. Deviating from the recommended heat range can lead to serious problems.

Electrode metal

The material used for the electrodes significantly impacts a spark plug's lifespan and performance characteristics:

• Iridium: This is the most common and recommended material for modern engines like those in the 2024 Sierra. Iridium is extremely hard and has a very high melting point, allowing for very fine electrodes. This design concentrates the spark, improving ignition efficiency and extending the plug's life significantly – often 100,000 miles or more. Both the 5.3L and 6.2L V8 engines utilize iridium-tipped plugs, as does the 2.7L Turbo.
• Platinum: Platinum plugs offer good durability and improved performance over copper, typically lasting around 60,000-80,000 miles. They are often found in engines that originally spec'd copper, as an upgrade, but are less common as OEM in brand-new vehicles designed for iridium.
• Copper: Copper plugs have a large-diameter center electrode, which provides a strong spark but wears relatively quickly. They are excellent conductors of electricity but their lower melting point means they have a shorter lifespan (typically 20,000-30,000 miles). They are rarely specified for modern engines with coil-on-plug ignition systems due to their shorter service life.

How to gap a spark plug

While most modern iridium spark plugs come pre-gapped from the factory, it's always a good idea to double-check the gap before installation, especially for the 2.7L Turbo engine which has a tighter tolerance. A spark plug gauge tool is essential for this process.

1. Identify the correct gap: Refer to the "Quick reference" table above for your engine's specific gap (in/mm).
2. Use a wire-type gap gauge: For modern plugs, especially those with fine iridium tips, a coin-style gap tool can damage the delicate electrode. A wire-type feeler gauge is the preferred method.
3. Check the gap: Gently slide the correct wire gauge between the center and ground electrodes. There should be a slight drag.
4. Adjust if necessary:
   • To increase the gap: Carefully use the gapping tool's adjustment slot to gently bend the ground electrode outwards. Bend incrementally to avoid over-gapping.
   • To decrease the gap: Gently tap the ground electrode on a hard, non-marring surface (like a wooden block) until the desired gap is achieved. Be extremely careful not to touch or damage the iridium tip.
5. Re-check: Always verify the gap after any adjustment.

Replacement procedure tips

Replacing spark plugs on a 2024 GMC Sierra 1500, regardless of the engine, involves similar steps with a coil-on-plug ignition system. Here are some key tips:

1. Engine Cool Down: Always ensure the engine is completely cool before starting. Attempting to remove or install spark plugs on a hot engine can damage the cylinder head threads.
2. Disconnect Battery: For safety, disconnect the negative terminal of the battery before starting work.
3. Coil-on-Plug (COP) Removal: Each spark plug has its own ignition coil mounted directly on top. Carefully disconnect the electrical connector from each coil, then unbolt the coil (typically a 7mm or 10mm bolt) and pull it straight up to remove it. Avoid prying, which can damage the coil or connector.
4. Clean Around Plugs: Before removing the old plugs, use compressed air to blow away any dirt or debris around the base of the plugs. This prevents contaminants from falling into the combustion chamber once the plugs are removed.
5. Anti-Seize Debate: There is an ongoing debate about using anti-seize on spark plug threads. For modern spark plugs with nickel-plated shells (as used in the Sierra 1500), anti-seize is generally not recommended by most manufacturers (including ACDelco, NGK, and Denso). The nickel plating acts as an anti-seize agent itself, and applying additional anti-seize can lead to overtightening and potential damage to the cylinder head threads, as anti-seize acts as a lubricant and affects torque readings.
6. Dielectric Grease on Boots: Apply a small amount of dielectric grease inside the spark plug boot (the end that connects to the spark plug). This helps lubricate the boot for easier installation and removal, seals out moisture, and prevents voltage leaks.
7. Torque Wrench is Crucial: Always use a calibrated torque wrench for installation. Overtightening can damage the spark plug or cylinder head threads, while undertightening can lead to combustion gas leaks, misfires, and overheating of the plug.

Known issues

Fortunately, the 2024 GMC Sierra 1500's engines generally do not have widespread "known issues" related to spark plug breakage or specific design flaws like some past Ford or GM engines (e.g., the infamous Ford 3-valve 2-piece spark plugs or early GM 5.3L ionization-sensing coils that required very specific plug types).

The most common issues you might encounter are typically related to improper maintenance:

• Fouling: If you experience consistent misfires, particularly in a single cylinder, it could indicate a fouled spark plug due to oil, fuel, or carbon buildup. This often points to a deeper engine issue that needs to be diagnosed.
• Heat Range Mismatch: Using aftermarket spark plugs with an incorrect heat range can lead to performance problems, pre-ignition, or premature plug failure. Stick to OEM or recommended aftermarket equivalents.
• Damaged Electrodes: Improper gapping techniques (using a coin-style tool on fine-wire plugs) or accidental drops can damage the delicate iridium tip or ground electrode, leading to misfires.

Adhering to the recommended spark plug type, gap, and torque specifications, along with timely replacement, will help ensure your 2024 GMC Sierra 1500 continues to run smoothly for many miles to come.

Need plugs replaced? Find a shop on Repairius.