Replace the Spark Plugs

Replacing the spark plugs on the Suzuki Swift Mk2 (RS, 2004–2010) restores a clean, reliable spark and smooths out rough idling or misfires. This guide covers the petrol engines only: the M13A 1.3, M15A 1.5, and the M16A 1.6 Sport.

Diesel owners, stop here. The 1.3 DDiS diesel Swift has no spark plugs at all — a diesel ignites fuel by compression and uses glow plugs (a cold-start aid) instead. This procedure does not apply to the diesel; nothing below should be attempted on a DDiS.

Plugs and gap for the petrol Swift

Suzuki specifies two options for the M13A, M15A, and M16A petrol engines. The iridium plug is highly recommended because it lasts far longer:

• Iridium: NGK IFR6J-11 — recommended, replace roughly every 105,000 km (63,000 miles) or 84 months on the normal schedule.
• Nickel (standard): NGK BKR6E-11 or DENSO K20PR-U11 — a shorter service life, around 30,000–45,000 km.

The “-11” in each part number denotes the 1.1 mm electrode gap. The owner manual gives an acceptable range of 1.0–1.1 mm (0.039–0.043 in.) for all three plug types. Always use the brand and type specified for your vehicle; the wrong thread size or heat range can damage the engine.

Tools you need

A 16 mm spark-plug socket (with a rubber insert to hold the plug), a ratchet and extension, and a torque wrench. A feeler/gap gauge is handy to check the gap, and a small amount of care is needed around the coil connectors.

How to replace the spark plugs

1. Let the engine cool completely. The plugs sit in the aluminum cylinder head and the threads can gall if you work on a hot engine. Park on level ground and switch the ignition off.
2. Remove the engine top cover / air cleaner assembly as needed. On this Swift the manual has you take out the four bolts fixing the air cleaner assembly and move it aside to reach the plugs, and to lift off the top cover. Keep the sealing rubber and washers from the cover safe so they go back correctly.
3. Disconnect and remove the ignition coils (ignitors). Most of these petrol engines use a coil-on-plug setup (one ignitor sitting directly on each plug), though some variants use ignition coils feeding HT leads: unplug the coil connector, remove the ignitor retaining bolt, and pull the coil straight up. Where a variant uses HT (high-tension) leads instead, pull on the boot, never on the cable — pulling the cable can damage it.
4. Blow out any dirt, then remove each plug. Clear grit from around the plug well so nothing falls into the cylinder, then loosen and unscrew each plug with the 16 mm socket. Do one plug at a time so you never mix up the firing order.
5. Check the new plug and its gap. Confirm the gap reads 1.0–1.1 mm. For iridium plugs, do not re-gap aggressively — the fine center electrode is fragile and bends/breaks easily; never touch or lever against the center electrode. Most iridium plugs come pre-gapped and need only a visual check.
6. Fit each new plug by hand first. Start the thread with your fingers (or the rubber socket insert) to avoid cross-threading the soft aluminum head. It should turn in smoothly and freely before you reach for the ratchet.
7. Torque the plug. The owner manual specifies 25 Nm (2.5 kg·m, 18 lb-ft). If you do not have a torque wrench, the plug maker’s turning-angle method is the fallback: seat the plug finger-tight against the head, then turn a new plug about a further half turn (a used plug with its gasket already crushed, about a sixteenth turn). Do not over-tighten.
8. Refit the coils and cover. Reinstall each ignitor/coil onto its plug, torque the ignitor bolt, reconnect the connectors, and refit the top cover and air cleaner assembly — checking the wires, couplers, sealing rubber, and washers are all seated correctly. Start the engine and confirm it idles smoothly with no warning lights.

If you notice hard starting or misfires after the job, the fault may be in aging ignition wiring rather than the new plugs — on cars with HT leads, Suzuki notes these are generally due for inspection after about 80,000 km or five years.

Frequently Asked Questions

Which spark plugs and gap does the petrol Suzuki Swift Mk2 use?

Iridium NGK IFR6J-11 (recommended) or nickel NGK BKR6E-11 / DENSO K20PR-U11. All are gapped to 1.1 mm (acceptable range 1.0–1.1 mm). This applies to the M13A 1.3, M15A 1.5, and M16A 1.6 Sport petrol engines.

How often should the spark plugs be replaced?

On the normal schedule, the recommended iridium plugs last about 105,000 km (63,000 miles) or 84 months. Nickel plugs are much shorter-lived — roughly 30,000–45,000 km. Severe-use driving shortens both intervals considerably.

Does the Suzuki Swift 1.3 DDiS diesel have spark plugs?

No. The DDiS diesel has no spark plugs — it ignites fuel by compression and uses glow plugs for cold starting instead. Spark-plug replacement is a petrol-only job.

If a check-engine light stays on or you suspect a misfire (a P0300-series fault code), read the stored code first to confirm the cause before replacing parts — see autodtcs.com.

This guide is for general information only. Always follow the official owner’s manual and service schedule for your exact vehicle, and consult a qualified mechanic if you are unsure. ServiceReset is not affiliated with Suzuki.