2024 Toyota Highlander Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2024 Toyota Highlander is crucial for optimal engine performance, fuel efficiency, and longevity. The "right plug" isn't just about fitment; it's about heat range, electrode materials, and precise gapping.

Heat range

Spark plugs are designed with a specific heat range, which determines how quickly heat is transferred from the firing tip to the cylinder head. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition and detonation, severely damaging your engine. A plug that's too "cold" (dissipates heat too quickly) can cause carbon fouling, leading to misfires and poor performance. Toyota engineers have carefully selected the ideal heat range for your Highlander's engine, so sticking to the OEM or recommended aftermarket plugs is vital.

Electrode metal

Spark plugs come with various electrode materials, each with different properties and lifespans:

• Iridium: These are the most common in modern vehicles like the 2024 Highlander. Iridium is extremely hard and has a high melting point, allowing for very fine electrodes that produce a more concentrated spark. This results in better combustion, fuel economy, and a much longer lifespan (typically 100,000+ miles).
• Platinum: Platinum plugs offer a good balance of performance and longevity, often lasting around 60,000 miles. They are a step up from copper but generally not as long-lasting as iridium.
• Copper: While copper is an excellent conductor, it's a softer metal and wears more quickly. Copper plugs are typically found in older vehicles or high-performance applications where more frequent changes are acceptable for a slightly stronger spark. They usually last around 30,000 miles.

Your 2024 Highlander's engines are designed for iridium-tipped plugs, which contribute to its extended service intervals and efficiency.

How to gap a spark plug

While many modern iridium spark plugs come pre-gapped from the factory, it's always a good idea to double-check the gap before installation. Incorrect gapping can lead to misfires, reduced power, and decreased fuel economy.

1. Use the correct tool: A wire-type spark plug gapping tool is generally preferred for iridium and platinum plugs. Avoid using coin-style gappers, as they can damage the delicate fine-wire electrode.
2. Measure: Carefully slide the appropriate wire gauge from your tool between the center and ground electrodes. It should slide with a slight drag.
3. Adjust if necessary: If the gap is too small, gently bend the ground electrode outwards using the gapping tool's adjustment feature. If the gap is too wide, gently tap the ground electrode on a clean, hard surface to close it slightly. Be extremely careful not to touch or bend the center iridium electrode.
4. Re-measure: Always re-measure after any adjustment to ensure accuracy.

Replacement procedure tips

Replacing spark plugs on your 2024 Toyota Highlander is a manageable DIY task for the mechanically inclined, but attention to detail is key.

• Coil-on-plug removal: Both engines in the 2024 Highlander utilize a coil-on-plug ignition system. This means each spark plug has its own ignition coil directly mounted above it. To access the plugs, you'll need to carefully disconnect the electrical connector from each coil and then unbolt and remove the coil. Often, a small pry tool can help with connector tabs, and a gentle twist can help free the coil from its well.
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