Spark Plug Gap Guide
Find the recommended spark plug gap for your engine type, fuel, and ignition system — plus plug type comparison and popular vehicle reference.
| Plug Type | Electrode | Life | Best For | Price |
|---|---|---|---|---|
| Copper / Nickel | Nickel alloy | 20,000–40,000 mi | Budget builds, older vehicles, carbureted engines | $ |
| Platinum (single) | Platinum tip on center electrode | 40,000–60,000 mi | Most modern vehicles | $$ |
| Double Platinum | Platinum on both electrodes | 60,000–100,000 mi | Wasted-spark ignition systems | $$ |
| Iridium | Iridium fine-wire center | 80,000–120,000 mi | Modern coil-on-plug engines, performance | $$$ |
| Laser Iridium | Iridium center + platinum ground | 100,000+ mi | OEM replacement on many Japanese vehicles | $$$ |
| Vehicle | Engine | OEM Plug | Gap | Note |
|---|---|---|---|---|
| Toyota Camry 2.5L | 2AR-FE / A25A | Denso SK20HR11 / NGK DILKAR7A11 | 0.044" | Laser iridium, do not adjust |
| Toyota Corolla 1.8L | 2ZR-FAE | Denso SK16HR11 / NGK ILZKAR8H8S | 0.044" | Laser iridium, do not adjust |
| Honda Accord 2.0T | K20C2 Turbo | NGK ILZKAR8H8S | 0.028" | Turbocharged — tight gap required |
| Honda Civic 1.5T | L15B7 Turbo | NGK ILZKAR8H8S | 0.028" | Turbocharged — tight gap required |
| Ford F-150 5.0L V8 | Coyote 5.0L | Motorcraft SP-579 | 0.052" | Coil-on-plug, replace all 8 |
| Ford F-150 3.5L EcoBoost | 3.5L Twin-Turbo V6 | Motorcraft SP-537 | 0.028" | Turbocharged — tight gap required |
| Chevy Silverado 5.3L | EcoTec3 5.3L V8 | ACDelco 41-162 | 0.040" | Iridium, 100k interval |
| Subaru WRX (EJ257) | EJ257 Turbo H4 | NGK DCPR7EIX | 0.028" | Turbocharged — tight gap required |
| BMW 328i / 330i (F30) | N20 / B48 2.0T | NGK LZKAR6AP-11 | 0.032" | Turbocharged |
| Mazda CX-5 2.5L | PY 2.5L Skyactiv | NGK SILZKR8C8S | 0.040" | High compression NA |
| Hyundai Sonata 2.5L | Theta III 2.5L | NGK IFR6T-11 | 0.044" | Iridium fine wire |
| Dodge RAM 5.7L Hemi | 5.7L Hemi V8 | Champion 9407 | 0.040" | Replace all 16 incl. dual plugs |
Always verify with your owner's manual or a manufacturer parts lookup. Pre-gapped iridium and laser iridium plugs should not be adjusted.
What Spark Plug Gap Does
The spark plug gap is the distance the spark must jump between the center electrode and the ground electrode. A wider gap creates a larger, hotter spark — improving combustion efficiency and fuel economy. However, too wide a gap requires higher voltage to fire and can cause misfires, especially under high load. Too narrow a gap produces a weak spark that burns fuel incompletely.
Why Forced Induction Needs a Smaller Gap
Turbochargers and superchargers increase air density in the cylinder. Denser air is harder for a spark to cross — the increased pressure effectively "stretches" the gap electrically. Running a standard gap in a boosted engine causes misfires under boost. High-performance turbo builds may run gaps as tight as 0.020–0.022" to maintain reliable ignition under high boost levels.
Symptoms of Worn or Incorrectly Gapped Plugs
Rough idle (especially when cold), engine misfires (felt as a stumble or shudder under acceleration), reduced fuel economy, slow throttle response, and failed emissions tests are all common signs. Many modern ECUs will set a P0300-series misfire code when a plug is worn or gapped incorrectly.
How to Gap a Spark Plug
Use a wire-type feeler gauge or a gapping tool. Never use flat feeler gauges on fine-wire iridium plugs — you will chip the electrode. For copper and platinum plugs, insert the correct wire gauge between the electrodes and bend the ground strap very gently. For laser iridium and OEM pre-gapped plugs, the manufacturer explicitly says do not adjust — install as-is.