CDI Box Igniter – Fits Yamaha 40HP Outboard Motors (Replaces 66T-85540-00, 66T-85540-01)
CDI Box Igniter – Fits Yamaha 40HP Outboard Motors (Replaces 66T-85540-00, 66T-85540-01) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
Restore reliable ignition performance in your Yamaha outboard with this direct-fit CDI Box Igniter. It is engineered for compatibility with a range of 40HP, 2-Stroke Yamaha engines, including 40X and E40X M(W/T)HS/L models from 1998–2013 and E40X MHL models from 2010–2017.
This module serves as a direct replacement for Yamaha OEM part numbers 66T-85540-00 and 66T-85540-01.
- Designed for plug-and-play installation with a 12-pin connector.
- Housed in durable ABS plastic to withstand marine environments.
- Provides stable ignition for 2-stroke gasoline outboard engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 66T-85540-00 |
| Yamaha | 66T-85540-01 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 40X M(W/T)HS/L | 40 | 2-Stroke | 1998–2013 | 66T-85540-00, 66T-85540-01 | |
| Yamaha | E40X M(W/T)HS/L | 40 | 2-Stroke | 1999–2009 | 66T-85540-00, 66T-85540-01 | |
| Yamaha | E40X MHL | 40 | 2-Stroke | 2010–2017 | 66T-85540-00, 66T-85540-01 |
Technical Specs
- Product Type
- CDI Igniter Box (Capacitor Discharge Ignition)
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Connection
- 12-Pin (8-pin + 4-pin connector)
- Housing Material
- ABS Plastic
- Housing Color
- Black
- Dimensions
- 11.5 in × 11.0 in × 6.0 in
- Weight
- 0.21 kg (0.46 lb)
- Fitting Type
- Direct plug-in
- Operating Voltage
- 12V
- Other Attributes
- Electronic ignition control module for 2-stroke outboard engines
What’s in the Box
- 1 x CDI Igniter Box (Replaces 66T-85540-00/66T-85540-01)
Installation Notes
For a safe and effective installation, first disconnect the battery. Locate and unplug the old CDI unit, paying attention to the connector and wiring. Carefully plug in the new CDI unit, ensuring the 12-pin connector is securely seated. Mount the unit in its original location, reconnect the battery, and test the engine's ignition system before full operation.
Troubleshooting & FAQ
How do I know if my CDI box has failed?
Common signs of a failing CDI box include the engine not starting, intermittent stalling, misfiring, backfiring, or a lack of spark at the plugs. A diagnostic test of the ignition system can confirm the failure.
Is this CDI unit compatible with my specific engine model?
This unit is designed for the Yamaha 40HP 2-stroke models listed in the compatibility table. Always double-check your engine's model number and year against our compatibility list before ordering.
What is the difference between this and the original Yamaha part?
This is an aftermarket part designed to meet or exceed OEM specifications for fit and performance. It offers a cost-effective alternative to the original Yamaha part without sacrificing quality or reliability.
Is any special programming or tuning required after installation?
No. This CDI module is a direct plug-and-play replacement. It comes pre-programmed to the factory ignition timing curve and requires no additional tuning.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
Payment methods
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