For most Honda Fit engines, the spark plug hex size is 5/8 inch (16 mm). Use a deep-well spark plug socket with a rubber insert sized to 5/8", and pair it with a suitable drive ratchet. Always verify the exact specification for your model year in the owner's manual or by inspecting the plug itself.
Understanding the right socket size
Knowing the correct hex size before you begin helps prevent damage to the spark plugs or the ignition system. While the Honda Fit predominantly uses a 5/8 inch hex, some older or non-U.S. market variants can use a different size. Confirm by checking the spark plug you’re removing or reviewing Honda’s official guidance for your exact model/year.
Commonly encountered sizes:
- 5/8 inch (16 mm) hex — standard for most Honda Fit engines (e.g., 1.5L i-VTEC and related variants).
- 13/16 inch (21 mm) hex — may appear on some older or alternate-market engines; verify before proceeding.
- Always confirm the exact size for your specific model/year to avoid stripping or cross-threading.
In practice, you’ll most often use a 5/8" spark plug socket for a Honda Fit. If you encounter a plug with a larger hex, switch to the corresponding 13/16" or other size as needed to ensure a proper fit.
Tools and steps for replacement
Below is a practical guide to replacing spark plugs on a typical Honda Fit. The steps assume you’re using a 5/8" deep-well spark plug socket with a rubber insert and a standard automotive toolkit.
- Tools you’ll need: 5/8" deep-well spark plug socket with rubber insert, ratchet (3/8" drive preferred), extension, torque wrench, the correct replacement plugs for your engine, and optional anti-seize or lubricant per manufacturer guidance.
- Prepare the engine area: Disconnect the negative battery terminal, remove any necessary covers or air intake ducts to access the spark plugs, and ensure the area is clean.
- Locate and remove the ignition coil: Detach the coil-on-plug connector and carefully remove the coil from the spark plug.
- Loosen and extract the old plug: Use the spark plug socket to loosen counterclockwise, then remove the plug with a steady, straight motion to avoid cross-threading.
- Inspect and prep the new plug: Verify the gap on the replacement plug as required, and apply a light coating of anti-seize or lubricant if recommended for your model.
- Install the new plug: Thread by hand to seat, then tighten to the manufacturer’s torque specification with a torque wrench to prevent over-tightening or under-tightening.
- Reassemble: Reconnect the ignition coil, reattach any removed covers or ducts, and restore the battery connection. Start the engine to verify smooth operation.
If you’re unsure about the correct torque or plug type for your exact year and trim, consult the owner’s manual or a qualified mechanic. Proper torque helps prevent stripping threads and ensures a reliable seal.
Summary
The Honda Fit typically uses a 5/8 inch (16 mm) spark plug hex, so a 5/8" deep-well spark plug socket is the standard tool for most models. Some older or market-specific variants may require a 13/16" (21 mm) socket. Always verify the exact size for your engine by checking the owner's manual or inspecting the current plug, and follow the recommended torque when installing a new plug.