6 HP 8 HP 9.9 HP 10 HP 15 HP 20 HP 25 HP Mercury Mariner Outboard 2 Stroke CDI Switch Box 855713A4
PRODUCT DETAILS
CDI Unit / Power Pack / Switch Box for Mercury & Mariner Outboards
Marine-grade aftermarket CDI ignition unit (power pack / switch box) replacing 855713A3 / 855713A4 on selected Mercury and Mariner 6, 8, 9.9, 10, 15, 20 and 25 HP 2-stroke, 2-cylinder outboards with a 4-magnet flywheel, approx. 1997–2006.
Fitment (approximate guide only)
- 6, 8, 9.9, 10 HP: approx. 1997–2005 (includes selected Sea Pro / Marathon)
- 15 HP: approx. 1997–2006
- 20 and 25 HP: approx. 1998–2006 (includes selected 25 XD, Sea Pro / Marathon)
All applications are 2-stroke, 2-cylinder with a 4-magnet flywheel. Mercury / Mariner used several ignition systems across these horsepowers, so horsepower and year alone do not confirm fitment, and a similar-looking unit is not always the right one.
Part numbers & cross references
- Replaces: 855713A3, 855713A4 (also listed as 855713-A3, 855713-A4, 855713)
- Cross reference: CDI Electronics 114-5713 / 1145713, Sierra 18-99222
- Not the earlier 339-7452A15 / A19 family used on approx. 1980–1997 engines. These are not interchangeable.
Before you order
Check your original CDI part number, plugs and wiring, cylinder count, flywheel type and full engine serial number. Faulty stator, trigger, coils, stop circuit or wiring can mimic CDI failure, so diagnose the full ignition system first. Unsure? Send SSI Marine your engine horsepower, complete serial number and a clear photo of your existing CDI and connections, and our technical team will identify the correct unit.
What's included
1 × new aftermarket CDI unit / power pack / switch box. This is a high-quality marine-grade aftermarket part, not a genuine Mercury, Mariner or Quicksilver component. OEM names and part numbers are for identification and compatibility reference only. Confirming compatibility before purchase is the buyer's responsibility.
Why buy from SSI Marine
- UK stock, workshop-tested parts, 10+ years with outboard engines
- Same-day dispatch before 1 PM Mon–Fri via Royal Mail Tracked 24
- Collection from Leigh, Greater Manchester. Workshop open Mon–Fri, 9 AM–5 PM
- Technical support from experienced outboard specialists
SHIPPING & DELIVERY
Delivery & Returns Policy
Delivery
Standard Delivery
- £6: Royal Mail Tracked 24 Service
- £3.99: Large Letter - Royal Mail 1st Class Post (Untracked)
We offer free delivery on all orders over £150 (excludes outboard engines).
Orders placed before 1:00 PM (Monday-Friday) are usually dispatched the same working day.
Most parcels are delivered within 24 hours, but please allow extra time for courier delays that may occur outside our control.
For outboard engines, please contact us for a delivery quote.
Important: Please ensure your shipping address is correct before completing checkout. SSI Marine is not responsible for parcels sent to an incorrect address provided by the buyer.
Tracking Your Order
Once your order has been dispatched, you will receive a tracking number via email (after 5 PM on the day of dispatch).
Tracking is available only for parcels sent via Royal Mail Tracked 24.
Large Letter orders are sent via Royal Mail 1st Class Post (untracked).
Returns
We accept returns of unused and undamaged items within 30 days of purchase.
Returned items must be in sellable condition and include the original packaging.
Please do not tape, label, or write directly on the product's original box.
Important: Do not return items in their original product boxes only, they must be placed inside a protective outer box or bag. Parcels returned like the example below will be subject to a 20% restocking fee.
Return shipping costs are the customer's responsibility.
Please include your order details and reason for return inside the parcel.
Refunds
Refunds are issued for the item purchase price only (shipping costs are non-refundable).
All refunds will be made using the same payment method as your original order.
Items returned in poor condition or without proper packaging may incur a 20% restocking fee.
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