Honda Civic Spark Plugs: Intervals, Fitment & Warning Signs
A genuinely useful piece of parts knowledge: the coil boot seal is separately replaceable — plus a real success story where fuel injector cleaner resolved a misfire that plugs and coils couldn't.
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OEM Part Number: 12290-R1A-A01 (as quoted in catalogue listings — confirm via engine code) — aftermarket NGK 95112 / Bosch 0 242 140 566
| Petrol engines in this generation | See the fitment notes |
|---|---|
| Spark plugs (aftermarket) | NGK 95112 (iridium, 14 mm hex, M12x1.25); NGK 95710 (iridium, 1.1 mm gap, M12x1.25); NGK 94742 (16 mm hex, M12x1.25); NGK 6774 (iridium, 16 mm hex, M14x1.25); Bosch 0 242 140 566 (0.7 mm gap, 14 mm hex, M12x1.25); Bosch 0 242 240 675 (1.1 mm gap, M14x1.25); Bosch 0 242 240 691 (1.3 mm gap, M14x1.25); Denso DXU22HCR-D11S (iridium/platinum, M12x1.25) |
| Genuine (OE) numbers quoted | Denso DXU22HCR-D11S (OE 12290-R1A-A01); Denso SKJ20DR-M11 (OE 9807B-561BW); Denso SKJ20DR-M13 (OE 9807B56A5W) |
| Fitment notes | Iridium plugs in M12x1.25 (NGK 95112, 95710, Champion OE277) and M14x1.25 (NGK 6774, Denso SKJ20DR) forms are both listed. Brisk 2099 lists a 100,000 km interval. No plug is tied to an engine code. |
A Genuinely Useful Piece of Parts Knowledge Worth Knowing — Honda Civic Spark Plugs
If a coil boot is showing signs of oil contamination or damage but the coil itself tests fine, this is genuinely worth knowing before buying a complete replacement coil unnecessarily: the upper seal (sometimes listed as "seal, plug hole") is available as a separate part from the entire coil assembly on many models. If it's specifically the seal that's failed — allowing oil to track down into the plug well — replacing just this seal can resolve the issue without the expense of a full coil, worth checking with a parts specialist before assuming the whole coil needs replacing.
It's also worth knowing about a genuinely distinctive, real cause worth ruling out if the car has aftermarket performance modifications: a lightweight flywheel or lightweight crank pulley has been documented as capable of causing false misfire codes across all cylinders simultaneously, with no genuine electrical or ignition fault present at all — one documented case took six months to correctly diagnose this as the actual cause. If you're chasing an otherwise unexplained multi-cylinder misfire code on a modified car, it's genuinely worth considering these specific components as a possible cause.
Honda Civic Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems
A worn set of spark plugs in the Honda Civic doesn't make itself obvious: idle roughens slightly, acceleration loses a bit of urgency, and both symptoms are easy to blame on something else entirely. Given how inexpensive the part is, it often gets neglected for far longer than it should.
Honda Civic Spark Plugs: Watch: Replacing It
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Honda Civic Spark Plugs: What They Do
Every combustion cycle in the Honda Civic's petrol engine starts with a spark plug igniting the compressed fuel-air mixture, and their condition shapes efficiency, economy and smoothness directly. Diesel versions don't need them at all, relying purely on compression to ignite fuel.
Honda Civic Spark Plugs: Generations & Spark Plug Count
| Diesel variants, where fitted | Not applicable — diesel engines use compression ignition and have no spark plugs at all |
|---|---|
| Petrol variants (all trims) | 4 spark plugs — one per cylinder |
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Honda Civic Spark Plugs: Warning Signs, DIY Difficulty & Aftermarket Advice
These are the same regardless of make or model — see our full Spark Plugs Guide for symptoms of worn plugs, why matching your exact plug specification matters, and trusted brands to buy from.
More Honda Spark Plugs
The same part, covered across other Honda models.