PRODUCT DETAILS
Genuine Honda NGK Iridium Spark Plug - 2017-2021 Civic Type R (12290-59B-003)
Tuned FK8 stumbling or throwing a misfire when the boost comes up, but running fine when you're just cruising? Start with the plugs. That's the classic symptom, and it's the first thing anybody who works on these cars checks. Cylinder pressure under boost is brutal on a spark plug, and a worn one can't hold a spark against it, so the ignition just blows out right when you're asking for everything. This is the genuine Honda NGK iridium plug, part 12290-59B-003, the exact plug your K20C1 was designed around. One important thing before you order: these are sold individually.
Yes, You Need Four
Let's get this out of the way, because it catches people constantly. Your K20C1 is a four-cylinder, and this listing is one plug. So set your quantity to 4 unless you're genuinely replacing a single fouled plug. And honestly? Don't do that either. Plugs wear as a set, and mixing one new plug in with three tired ones just means you're back in there soon. Do all four at once, it's the same amount of work.
Why The Right Plug Matters More On A Turbo Car
Here's what people miss about plugs on a boosted motor. On a naturally aspirated car, a slightly wrong plug is mostly a nuisance. On the K20C1, it's a real risk. This plug's heat range was chosen by Honda specifically for what happens inside a turbocharged Type R combustion chamber, hot enough to stay clean, cold enough to pull heat out of the chamber before it can light the mixture off early. Get that wrong and you're flirting with pre-ignition, and pre-ignition on a boosted K20 doesn't give you a warning, it gives you a broken ringland. Running the plug Honda spec'd is genuinely the cheap insurance here.
What Iridium Buys You
The iridium tip is why these last the way they do. Iridium is brutally hard and handles heat, so the fine center electrode holds its shape for tens of thousands of miles instead of eroding and opening up the gap the way copper does. And that fine electrode takes less voltage to fire, which matters on a turbo car where your coils are already fighting cylinder pressure. Less strain on the ignition system, more consistent spark when it counts.
Don't Gap These
Real advice that saves people money: iridium plugs come pre-gapped from the factory and you should leave them alone. That fine center electrode is precise and it's fragile, and going at it with a traditional gapping tool is how you snap the tip clean off or bend the ground strap into the electrode. Then you've got a ruined plug that looks fine sitting in your hand. Check the gap if it makes you feel better, but don't adjust it unless you know exactly what you're doing and why.
Same goes for install: these thread into an aluminum head, so snug them to spec and stop. Gorilla-tighten a plug into aluminum and you'll find out what stripped threads cost.
A Note For Tuned Cars
Straight talk if you're modified. This is the OEM heat range plug, and it's the correct choice for a stock or bolt-on FK8, including most FlashPro or KTuner street tunes. But if you're running serious boost, E85, or a built setup making real power, talk to your tuner about whether you want to step a range colder. Plugs are also a wear item that a tune accelerates, so if your car's tuned, check them more often than the factory interval suggests. They're cheap. Pistons aren't.
What You Get
- Genuine Honda NGK iridium spark plug, part 12290-59B-003
- OEM heat range for the K20C1 turbocharged engine
- Iridium center electrode for long life and easy firing
- Pre-gapped from the factory
- Sold individually (four required per engine)
Fits These Cars
- 2017-2021 Honda Civic Type R (FK8, K20C1)
Note: Sold individually. Four are required for a complete set. Pre-gapped from the factory; do not re-gap. This is the OEM heat range plug, suitable for stock and bolt-on applications. Heavily modified or high-boost builds should consult a tuner regarding heat range.