Arco IG012 Ignition Coil — Mercury Outboard 135–300HP (1998–2006)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
OEM-Grade Ignition Coil for Mercury High-Output Outboards
The Arco IG012 is a direct-fit replacement ignition coil engineered for Mercury high-output outboard engines in the 135HP through 300HP range, covering the 1998 through 2006 production window. This coil is a precision match for the original ignition coil assembly used on these powerful Mercury powerheads and is a reliable choice for restoring strong, consistent spark output.
Compatible Applications
- Mercury Outboard 135 HP (1998–2006)
- Mercury Outboard 200 HP (1998–2006)
- Mercury Outboard 225 HP (1998–2006)
- Mercury Outboard 250 HP (1998–2006)
- Mercury Outboard 300 HP (1998–2006)
Replaces OEM Part Numbers
- Mercury: 339-850227, 339-856991A1
- Sierra: 18-5187
- CDI Electronics: 184-0005
Parts Desk Insights
The IG012 covers the high-output Mercury outboard range from the late 1990s through the mid-2000s — a generation of engines known for strong performance but also for ignition coil failures as they age. It’s the right part to reach for when diagnosing a dead or misfiring cylinder, hard starting, or RPM-related spark dropout on a 135–300HP Mercury from this era. Because Mercury used different coil designs across model years and engine families, always cross-reference your engine’s OEM part number before ordering. For Mercury outboard coil applications from 2004 onward across a broader HP range, compare with the Arco IG005 Ignition Coil. For DFI and EFI Mercury outboard and performance sterndrive coil applications, see the Arco IG011 Ignition Coil.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
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.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.