2019 Nissan Altima: Spark Plug Specifications

Quick reference

Why the right plug matters

Spark plugs are a critical component of your vehicle's ignition system, responsible for igniting the air-fuel mixture in the combustion chamber. Using the correct spark plug is essential for optimal engine performance, fuel efficiency, and longevity. The 2019 Nissan Altima, depending on the engine, uses high-performance iridium-tipped spark plugs from the factory. Iridium is a precious metal that is harder and has a higher melting point than platinum or copper, allowing for a very fine center electrode. This fine-wire design creates a more focused and consistent spark, leading to better throttle response and improved fuel economy. In contrast, older copper plugs have a larger electrode and wear out much faster, typically needing replacement every 30,000 miles, while modern iridium plugs can last for 100,000 miles or more. The "heat range" of a plug is also critical; it determines how quickly the plug dissipates heat. A plug that is too "hot" can lead to pre-ignition (detonation), while a "cold" plug can foul more easily. For these reasons, it is always recommended to use the OEM-specified plug or a high-quality equivalent from a reputable brand like NGK or Denso.

How to gap a spark plug

Spark plug "gap" is the distance between the center and ground electrodes, and it must be set precisely. Even brand-new plugs should be checked before installation. Use a feeler gauge or a dedicated wire-type spark plug gapper to measure the gap. If adjustment is needed, do not pry against the center electrode, especially on fine-wire iridium plugs, as this can easily break it. Instead, gently bend the ground strap (the J-shaped electrode) by lightly tapping it on a hard surface to close the gap or using the lever tool on a gapper to open it. Re-measure until the correct specification is reached. For the 2.5L engine, the gap is 0.044 inches (1.1mm), and for the 2.0L Turbo, it is a tighter 0.032 inches (0.8mm) to prevent spark blow-out under boost.

Replacement procedure tips

The 2019 Altima uses a modern coil-on-plug ignition system, which means each spark plug has its own individual ignition coil. The procedure is straightforward: remove the engine cover, disconnect the electrical connector from the coil, unbolt the coil, and pull it straight up and out. The spark plug is then accessible deep in the cylinder head. Use a spark plug socket with a rubber insert to grip the plug during removal and installation. A topic of frequent debate is the use of anti-seize compound on the plug threads. Modern NGK plugs have a special trivalent plating that provides anti-seize properties, and they specifically recommend against using additional lubricant, as it can lead to over-torquing and potential thread damage. When installing the new plugs, always thread them in by hand first to avoid cross-threading, then use a torque wrench to tighten them to the exact specification (13-15 lb-ft). A small amount of dielectric grease applied to the inside of the coil boot (not on the connector pins) can prevent the boot from sticking to the plug's ceramic insulator and make future removal easier.

Known issues

Unlike some older engines famous for problematic spark plug designs (like the Ford 3-valve Triton engines with their two-piece plugs that would often break), the engines in the 2019 Nissan Altima have no widespread, known issues related to spark plug design or replacement. The direct-injected PR25DD and KR20DDET engines use a conventional, one-piece spark plug design that is reliable and easy to service. Following the correct procedure—using the right tools, checking the gap, and torquing to spec—should result in a trouble-free spark plug replacement job.

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