The spark plug socket size you need for a 2018 Honda Accord is a 5/8-inch (16 mm) deep-well spark plug socket with a rubber insert. This size fits the standard iridium spark plugs used in the model’s 1.5L and 2.0L engines. Always verify by checking the plug hex on your specific plugs if you have aftermarket parts.
In practice, most 2018 Accords—whether powered by the 1.5-liter turbocharged four or the 2.0-liter turbocharged four—use plugs with a 5/8-inch hex. The tool setup is designed to reach the plugs under the coil packs and protect the delicate threads. Let’s break down what this means for your maintenance work.
Socket size and why it matters
Understanding the right socket size helps prevent damaged plugs and stripped hexes. Using a socket that’s too large or the wrong type can slip off, while a socket that’s too small won’t grip. The 5/8-inch hex size is by far the most common choice for Honda’s 2018 Accord plugs, but you should always confirm with your plug’s packaging or the owner's manual.
Engine variants and practicality
The 2018 Accord was offered with a 1.5L turbocharged engine and a 2.0L turbocharged engine. Both typically use the same 5/8-inch hex spark plugs, meaning a single 5/8" spark plug socket will usually suffice for either engine. Access can vary due to coil placement, so a deep-well socket, a 3/8" drive ratchet, and a short (or flexible) extension can help.
What tools to use
Before you begin, assemble the essential tools that pair with a 5/8" spark plug socket to ensure you can reach the plugs safely and torque them correctly after installation.
- Deep-well spark plug socket with rubber insert in 5/8-inch hex
- 3/8-inch drive ratchet or appropriate driver
- Swivel or universal joint and a short extension for access around coil packs
- Torque wrench for re-tightening to spec
- Spark plug gap gauge and the recommended gap for Honda plugs
With the right socket in hand, you are prepared for a relatively straightforward maintenance task, provided you follow proper safety and torque guidelines.
Steps to replace spark plugs on a 2018 Accord
Follow these steps to replace your spark plugs correctly, keeping in mind that the order doesn’t significantly affect most four-cylinder engines, but you should work methodically to avoid cross-threading and keep debris away from the cylinders.
- Disconnect the negative battery terminal and disable any accidental startup safeguards as per vehicle manual.
- Remove the engine cover and any coil-on-plug assemblies to expose the spark plugs.
- Carefully thread the old plugs out with the 5/8" socket and extension, avoiding force or sudden movements.
- Check the new plugs’ gap to the manufacturer’s specification (commonly around 0.043–0.044 inches for many Honda engines).
- Install the new plugs by hand to avoid cross-threading, then torque to specification.
- Reassemble coil packs, engine cover, reconnect battery, and test the engine to ensure a smooth idle.
Following these steps with the correct socket ensures a safe replacement that preserves engine performance and longevity.
Summary
The standard spark plug hex size for the 2018 Honda Accord is 5/8-inch (16 mm). Using a deep-well 5/8" spark plug socket with a rubber insert, on a compatible drive, is the typical approach for both the 1.5L and 2.0L turbo engines. Always verify the hex size on your plugs and refer to the owner’s manual or plug packaging, and prepare with the right extensions and torque tools for a successful replacement.