The correct spark plug gap for a 2013 Honda Civic LX with the 1.8-liter engine is 0.043–0.047 inches (1.10–1.20 mm).
That gap range applies to the R18A1 engine used in that model year and covers common plug types such as copper, platinum, or iridium. Maintaining the correct gap is important for smooth idling, optimal fuel economy, and reliable ignition. Always verify the exact spec in Honda's service data for your VIN and chosen plug brand, since recommendations can vary slightly by plug type or production batch.
Spark plug gap specification
Officially, Honda's service information for the 2013 Civic LX 1.8 L lists a target gap of 0.043–0.047 inches (1.1–1.2 mm) for the R18A1. If you replace plugs from different brands, ensure they are the correct heat range and re-check the gap after installation.
Plug type and compatibility
Choosing a plug approved for the R18A1 engine is essential. Most technicians use reputable brands such as NGK or Denso and maintain the 0.043–0.047 in gap unless the plug’s packaging specifies a different gap.
How to check and set the gap
Follow these steps to verify and adjust the spark plug gap on a 2013 Civic with a 1.8 L engine.
- Prepare the tools: spark plug socket, torque wrench, and a straight-feeler gauge set.
- Remove the spark plug cap/boot and the plug; inspect for damage and clean threads.
- Check the new or inspected plug’s gap with a feeler gauge and set to 0.043–0.047 inches (1.10–1.20 mm) if needed. Do not force-gap a plug excessively; if the gap cannot be achieved, replace with a correctly gapped plug.
- Reinstall the plug and torque to the recommended specification (typically around 13–16 ft-lbs / 18–22 Nm; verify in service data).
- Reconnect the ignition boot and ensure the coil/boot is seated properly.
Concluding: With the gap set within 0.043–0.047 inches, the engine should fire reliably, maintain good fuel economy, and idle smoothly. Always verify torque specifications and the exact gap for your chosen plug in the Honda service data.
Summary
Short answer: 0.043–0.047 inches (1.10–1.20 mm). For best results, use the approved plug type for your engine, verify the gap after installation, and consult the service manual or a Honda dealer for the exact specification for your VIN.