On the 2018 Honda Fit with the 1.5-liter engine, the spark plug gap recommended by Honda is 0.043–0.047 inches (1.10–1.20 mm). This range covers most OEM and aftermarket plugs designed for the engine. Always verify the gap specified by the plug manufacturer and consult the owner's manual for your exact vehicle configuration.
Official gap specification for the 1.5L engine
The 2018 Fit's 1.5L engine relies on a precise gap to ensure reliable ignition, good fuel economy, and smooth operation. The commonly cited Honda spec is 0.043–0.047 inches (1.10–1.20 mm). Plug types or brands may ship pre-gapped differently, but you should adjust to this range if you are using any plug other than the original equipment.
Notes on plug types and variations
Most replacement plugs for the 1.5L engine—whether copper, platinum, or iridium—are designed to be gapped to the same range. If a specific plug instruction indicates a different gap, you can still bring it within the 0.043–0.047 inch window before installation.
Before listing the practical steps, here is a concise checklist of key points drivers should know about gap values.
- The standard gap range for the 2018 Fit is 0.043–0.047 inches (1.10–1.20 mm).
- Variants may include 0.043, 0.044, 0.047 inches; confirm your plug's data sheet to stay within the Honda spec.
- All replacement plugs should be gapped to spec prior to installation to prevent misfires or rough running.
In summary, maintain the gap within 0.043–0.047 inches to ensure optimal ignition and performance. If your chosen plugs come pre-gapped differently, adjust accordingly, then re-check after installation.
How to check and adjust the spark plug gap
For drivers who prefer to do the work themselves, follow these steps to verify and set the gap to the factory spec.
- Assemble the right tools: a spark plug socket with a rubber insert, a feeler gauge set that includes 1.0 mm to 1.5 mm, and a basic torque driver or wrench if you intend to reinstall the plug.
- Identify the correct spark plug and ensure it is the right heat range and thread size for the 2018 Fit's 1.5L engine.
- Carefully disconnect the ignition coil or spark plug boot, then remove the spark plug from the cylinder head using the socket.
- Inspect the plug for wear, fouling, cracks, or excessive electrode wear; replace if necessary rather than re-gap and reuse severely worn plugs.
- Measure the gap with the feeler gauge by inserting the appropriate blade (0.043 to 0.047 inches / 1.10 to 1.20 mm) between the center electrode and ground electrode. The gap should slide in with a slight resistance.
- If the gap is too small, widen it by gently bending the ground electrode; if too large, carefully bend the ground electrode toward the center to close the gap. Do not force the center electrode or apply lateral stress that could damage the insulator.
- Re-measure with the feeler gauge to confirm the gap is within 0.043–0.047 inches. Repeat adjustments as needed.
- Reinstall the plug and tighten to the vehicle’s specified torque. If you do not have the torque spec, refer to the owner's manual or service manual for the exact value and avoid over-tightening.
- Reconnect the ignition coil/boot and run the engine to verify a smooth idle and proper ignition. If misfires or rough running persist, inspect wiring and the plug again or replace with a new plug.
The above steps help ensure you maintain the correct gap and plug condition to preserve engine performance and fuel efficiency.
Summary
For a 2018 Honda Fit, the spark plug gap should be within 0.043–0.047 inches (1.10–1.20 mm). This range applies to standard OEM plugs and commonly used aftermarket options. Always verify the specific plug’s instructions and follow the vehicle’s service manual for torque values and reinstallation steps. If in doubt, have a certified mechanic perform the replacement or gap adjustment to ensure proper engine performance.