Champion RN9YC Spark Plug | #415 | 4-Pack | Marine Inboard & Sterndrive
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Hotter Heat Range Spark Plug for Marine Inboard and Sterndrive Engines — 4-Pack.
The Champion RN9YC is a projected-tip, resistor-type spark plug for marine inboard and sterndrive engines. Part number 415, the RN9YC runs one heat range hotter than the Champion RN12YC #404 — making it the correct choice for engines that run cooler or at lower average RPM, where a hotter plug helps burn off carbon deposits and maintain a clean electrode.
The YC-suffix design features a projected tip for improved ignitability and a built-in resistor to suppress radio frequency interference. Sold in a 4-pack (Champion part 44165). Always verify fitment against your engine's owner's manual or Champion application guide before ordering.
Key Features
- Champion RN9YC spark plug — 4-pack (Champion #415)
- Hotter heat range than the RN12YC — for cooler-running or lower-RPM marine inboard applications
- Projected tip for improved ignitability and combustion efficiency
- Built-in resistor suppresses radio frequency interference (RFI)
- Copper core electrode for reliable heat transfer and consistent spark
Compatible Applications
- MerCruiser sterndrive engines specifying Champion RN9YC or equivalent
- GM/Chevrolet V8-based marine inboard engines specifying RN9YC or equivalent
- Ford V8-based marine inboard engines specifying RN9YC or equivalent
- Cooler-running or lower-average-RPM marine inboard engines where a hotter plug is specified
- Any application cross-referencing Champion #415 or part 44165
- Verify fitment using your engine's owner's manual or the Champion spark plug application guide
Parts Desk Insights
The RN9YC is the hotter sibling of the Champion RN12YC #404 — if your engine specifies the RN9YC, use the RN9YC. A hotter plug is appropriate when your engine runs cool and you're seeing carbon fouling on the electrode. If your engine specifies the RN12YC, don't substitute the RN9YC thinking a hotter plug is always better — a plug that's too hot for the application can cause pre-ignition and engine damage.
For other ignition components for MerCruiser and sterndrive engines, browse our Ignition Components collection. For NGK alternatives in marine inboard applications, see the NGK BPR6ES.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
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