2017 Toyota Corolla Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2017 Toyota Corolla is more critical than many car owners realize. Spark plugs are not one-size-fits-all components; they are carefully engineered to work in harmony with your engine's specific design. The heat range of a spark plug is paramount. A plug that is too "cold" won't get hot enough to burn off carbon deposits, leading to fouling and misfires. Conversely, a plug that is too "hot" can overheat, causing pre-ignition, detonation, and potentially severe engine damage. The OEM plugs listed for your Corolla are precisely chosen by Toyota for the optimal heat range to ensure efficient combustion and long engine life.

The electrode material also plays a significant role in performance and longevity. Your 2017 Corolla came from the factory with iridium spark plugs. Iridium is an incredibly hard and durable precious metal, allowing for very fine electrodes that produce a strong, consistent spark. This translates to better fuel efficiency, smoother idling, and extended service intervals.

• Iridium plugs (like those found in your Corolla) offer the best combination of performance and longevity, typically lasting 100,000 miles or more. They are the most expensive but also the most cost-effective in the long run due to their durability.
• Platinum plugs are a step down from iridium but still offer good longevity (around 60,000-80,000 miles) and improved performance over copper.
• Copper plugs are the least expensive and provide excellent conductivity, but their softer electrodes wear down more quickly, requiring more frequent replacement (typically every 30,000 miles).

Never "downgrade" to a copper plug if your engine originally specified iridium or platinum. The performance and longevity will suffer, and you may encounter engine issues.

How to gap a spark plug

While most modern iridium spark plugs come pre-gapped and it's generally recommended not to adjust them due to the delicate nature of the fine iridium electrode, if you do need to check or adjust the gap, it's crucial to do so correctly. Your 2017 Corolla requires a gap of 0.043 inches (1.1 mm).

Use a wire-type spark plug gapping tool, not the wedge-style. The wedge-style tool can damage the delicate iridium tip. Carefully slide the correct thickness wire gauge between the center and ground electrodes. If adjustment is needed, gently bend only the ground electrode using the gapping tool. Never apply pressure to the center electrode or the ceramic insulator. Excessive force can easily damage the plug, leading to misfires or premature failure.

Replacement procedure tips

Replacing the spark plugs on your 2017 Toyota Corolla is a relatively straightforward procedure for a DIY enthusiast, but a few tips can make it smoother:

1. Coil-on-Plug Removal: Your Corolla uses a coil-on-plug ignition system. This means each spark plug has its own individual ignition coil mounted directly above it. To access the spark plugs, you'll need to disconnect the electrical connector from each coil and then remove the bolt (usually a 10mm) securing the coil to the valve cover. Once the bolt is out, gently twist and pull the coil straight up to remove it. Avoid yanking on the electrical connector wires.
2. Anti-Seize Debate: There's ongoing debate about using anti-seize on spark plug threads. For spark plugs with a nickel-plated shell (which many modern plugs, including iridium, are), manufacturers like NGK and Denso generally recommend against using anti-seize. The nickel plating provides sufficient corrosion resistance, and anti-seize can act as an electrical insulator, affecting accurate torque readings, potentially leading to over-tightening and plug damage or stripping the cylinder head threads. Follow the spark plug manufacturer's recommendation.
3. Dielectric Grease on Boots: It's a good practice to apply a small amount of dielectric grease to the inside of the spark plug boot (the rubber part that fits over the top of the spark plug). This helps lubricate the boot for easier removal in the future, prevents moisture intrusion, and improves insulation, helping to prevent misfires.
4. Torque is Key: Always use a torque wrench when installing new spark plugs. The recommended torque for your 2017 Corolla is 13 lb-ft (18 Nm). Under-tightening can lead to plugs vibrating loose and causing damage, while over-tightening can strip the cylinder head threads or crack the spark plug insulator.
5. One at a Time: To avoid dropping debris into an open cylinder, work on one spark plug at a time. Remove the coil, remove the old plug, install the new plug, and then reinstall the coil before moving to the next cylinder.

Known issues

The 2017 Toyota Corolla, equipped with the 2ZR-FE or 2ZR-FAE engine, generally does not suffer from well-known chronic spark plug-related issues like the Ford 3-valve engine's two-piece spark plug breakage or GM 5.3L engine's ionization sensing coil problems.

However, watch for common symptoms of failing spark plugs, such as:

• Engine misfires: A noticeable stumble or hesitation, especially under acceleration.
• Reduced fuel economy: The engine isn't burning fuel efficiently.
• Rough idle: The engine feels shaky at idle.
• Check Engine Light (CEL): A P030x code (e.g., P0301 for cylinder 1 misfire) will likely accompany severe misfires.

These symptoms, when plugs are due for replacement, indicate it's time for new spark plugs to restore optimal engine performance and efficiency.

Need plugs replaced? Find a shop on Repairius.