2018 Toyota Corolla Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2018 Toyota Corolla is crucial for optimal engine performance, fuel efficiency, and longevity. The spark plug is responsible for igniting the air-fuel mixture in your engine's combustion chambers. A plug that is too hot or too cold, or has an incorrect gap, can lead to a host of problems.

Heat Range: Spark plugs are designed with a specific heat range, which determines how quickly they dissipate heat from the combustion chamber. A "hot" plug retains more heat, while a "cold" plug dissipates it faster. An incorrect heat range can lead to pre-ignition (where the fuel ignites before the spark) or fouling (where carbon deposits build up on the plug), both of which can damage your engine.

Electrode Metal: The material of the spark plug electrode significantly impacts its lifespan and performance. The 2018 Corolla's 1.8L engine comes with iridium spark plugs from the factory. Iridium is a very hard and durable metal that allows for a finer electrode tip, which in turn creates a more concentrated and efficient spark. This is why iridium plugs boast extended replacement intervals, typically around 100,000 to 120,000 miles.

While platinum plugs offer a longer lifespan than traditional copper plugs, they don't quite match iridium's durability and efficiency. Copper plugs, though excellent conductors, have a much shorter lifespan due to their softer electrode material and larger tip, requiring more frequent replacement.

How to gap a spark plug

The spark plug gap is the distance between the center electrode and the ground electrode. An accurately gapped plug ensures a strong, consistent spark. For your 2018 Toyota Corolla's 1.8L engine, the specified gap is 0.043 inches (1.1 mm).

To gap a spark plug, you'll need a spark plug gapping tool. A wire-type gauge is generally preferred for iridium and platinum plugs to avoid damaging the fine electrode tip. Carefully slide the correct thickness gauge wire between the electrodes. If the gap is too small, gently bend the ground electrode outwards with the gapping tool. If the gap is too large, you can carefully tap the ground electrode on a hard, non-abrasive surface to close it slightly. Always recheck the gap after making any adjustments. Be extremely careful not to apply force to the center iridium electrode, as it can be easily damaged.

Replacement procedure tips

Replacing the spark plugs on your 2018 Toyota Corolla with the 1.8L (2ZR-FE) engine is a straightforward process, but a few tips can make it smoother:

1. Coil-on-plug removal: Your Corolla uses a coil-on-plug ignition system, meaning each spark plug has its own ignition coil directly on top of it. To access the plugs, you'll need to disconnect the electrical connector from each coil and then remove the retaining bolt (usually 10mm). Gently pull the coil straight up and off the spark plug. Avoid twisting or prying them, as this can damage the coil or its boot.
2. Anti-seize debate: There's an ongoing debate about applying anti-seize compound to spark plug threads. Some manufacturers, including Toyota, do not recommend it for modern spark plugs with nickel-plated shells, as it can alter the torque readings and potentially lead to over-tightening. If you choose to use anti-seize, apply it very sparingly and reduce the torque specification by about 10-15%.
3. Dielectric grease on boots: Apply a small amount of dielectric grease to the inside of the spark plug boots (the part that connects to the spark plug porcelain). This helps prevent moisture entry, insulates against voltage leaks, and makes future removal easier.

Known issues

Fortunately, the 2018 Toyota Corolla's 1.8L engine is not known for any specific endemic spark plug issues like the cracked porcelain on some Ford 3-valve engines or broken plug shells. Using the correct spark plugs and following the recommended maintenance schedule will help ensure trouble-free operation.

Need plugs replaced? Find a shop on Repairius.