2020 Toyota Corolla Spark Plug Replacement Guide

Quick Reference

Why the right plug matters

The spark plugs in your Corolla's engine are small, but they play a huge role in performance and fuel economy. Using the correct spark plug is critical. Here's why:

• Heat Range: Spark plugs are designed with a specific heat range to either dissipate heat quickly (cold plug) or hold onto heat (hot plug). The 2020 Corolla, with its modern, efficient engines, requires a specific heat range to prevent pre-ignition (knock) and fouling. Using the wrong heat range can lead to engine damage.
• Electrode Metal: The 2020 Corolla uses long-life iridium spark plugs from the factory. While platinum and copper plugs are available, they will not last as long as the original iridium plugs. Iridium is an extremely hard and durable precious metal, which allows for a very fine center electrode. This fine wire design creates a more concentrated spark for better ignition and can last up to 120,000 miles.

How to gap a spark plug

Properly gapping your spark plugs is a critical step. While many modern iridium plugs come pre-gapped, it's always a good idea to double-check them.

1. Use a wire-style or feeler gauge: Do not use the old "coin-style" gapping tools, as they can damage the fragile iridium tip.
2. Slide the gauge between the electrodes: You should feel a slight drag. If the gap is too tight, you can gently bend the ground strap up. If it's too wide, you can lightly tap the ground strap on a hard surface to close the gap.
3. Be gentle: The iridium center electrode is very brittle. Do not put any pressure on it.

Replacement procedure tips

Replacing the spark plugs on your 2020 Corolla is a straightforward job.

• Coil-on-plug removal: Both the 1.8L and 2.0L engines in the 2020 Corolla use a coil-on-plug ignition system. This means each spark plug has its own ignition coil directly on top of it. To access the plugs, you will need to remove a single bolt holding each coil in place and then gently twist and pull the coil straight up.
• Anti-seize debate: There is a lot of debate about whether to use anti-seize on spark plug threads. The short answer is: don't. NGK and Denso, the OEM suppliers for Toyota, coat their plugs with a special anti-corrosion plating that also acts as a release agent. Adding anti-seize will alter the torque readings and can lead to over-tightening and damaged threads in the aluminum cylinder head.
• Dielectric grease: It is a good practice to apply a small amount of dielectric grease to the inside of the spark plug boot before reinstalling the ignition coil. This helps to seal out moisture and prevent the boot from sticking to the spark plug porcelain.

Known issues

Fortunately, the 2020 Toyota Corolla and its engines have no widespread, known issues related to spark plugs. The era of problematic designs like the Ford 3-valve two-piece plugs that would break off in the head are, thankfully, not a concern on this vehicle.

Need plugs replaced? Find a shop on Repairius.