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Knock Sensor 3854905 – Volvo Penta 4.3/5.0/5.7L Stern Drive
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How to Match This Part
This aftermarket knock (detonation) sensor replaces Volvo Penta 3854905 on gasoline stern drive / Out Drive packages. It threads into the engine block, monitors combustion vibration, and signals the control module so ignition timing can be retarded when knock is detected.
Match this part in this order:
1. OEM number on the sensor you are removing or in your parts catalog — 3854905
2. Engine model code and year on the Volvo Penta engine identification plate (see Compatible Engines below)
3. Aftermarket cross — Sierra 18-7679 if that is what your catalog lists
Compare the product images to the part on your engine: cylindrical metal body, single-pin terminal post on top, and a threaded mounting stud with pre-applied sealant on the threads. Confirm the OEM number before ordering — other knock sensors exist for different stern-drive families.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers. 3854905 is the primary Volvo Penta reference for this listing.
| Type | Brand | Part Number | Notes |
|---|---|---|---|
| Primary OEM Reference | Volvo Penta | 3854905 | Original equipment knock sensor |
| Aftermarket | Sierra Marine | 18-7679 | Direct replacement cross |
Part numbers are listed for identification only. This is an aftermarket part manufactured by JLM Marine and is not sold as a genuine Volvo Penta component.
Compatible Engines
Confirm your Volvo Penta stern drive / Out Drive model designation and year on the engine identification plate, and that the removed sensor is numbered 3854905 (or Sierra 18-7679). Do not expand beyond the models listed here.
| Displacement | Engine Model | Years |
|---|---|---|
| 4.3L | 4.3L stern drive | 1994–2002 |
| 5.0L | 5.0L Gxi-A | 2001–2002 |
| 5.7L | 5.7L GiL-A | 2001 |
| 5.7L | 5.7Gi-A, 5.7GXi-A, 5.7GXi-B, 5.7GiI-A, 5.7GSiI-A, 5.7GXiI-A, 5.7GXiI-B | 2000–2003 |
| 5.7L | 5.7GLPNCS, 5.7GIPNCACE, 5.7GIPNCSCE, 5.7GIPNCMCE, 5.7GIPNCBCE, 5.7GIINCCCE, 5.7GIINCSCE | 1995–1996 |
Important: This listing covers the gasoline stern-drive packages above. Verify the OEM number on your engine before ordering — other Volvo Penta knock sensors are used on different engine families.
Technical Specifications
| Specification | Value |
|---|---|
| Part type | Knock / detonation sensor |
| Primary OEM number | 3854905 |
| Engine application | Volvo Penta gasoline stern drive / Out Drive, 4.3L / 5.0L / 5.7L |
| Aftermarket cross | Sierra 18-7679 |
| Terminal style | Single-pin connector post (no harness supplied) |
| Mounting | Threaded stud with pre-applied thread sealant; screws into the engine block |
| Function | Detects knock / detonation and signals the ECM for timing retard |
Installation Guide
1
Disconnect the battery and allow the engine to cool. Locate the existing knock sensor on the block and note harness routing before unplugging.
2
Unscrew the old sensor with a deep socket. Clean the block threads and mounting face so the new sensor can seat metal-to-metal.
3
Compare body shape, stud length, and single-pin terminal to the part you removed and to the product images. Do not add extra sealant, tape, or washers — the stud already carries thread sealant, and the sensor needs direct metal contact to read block vibration.
4
Thread the sensor in by hand, then tighten to the torque specified in your Volvo Penta service manual for this application. Over-tightening can damage the sensing element.
5
Reconnect the harness until fully seated, reconnect the battery, clear any stored knock-sensor codes if present, and confirm normal operation under load.
Note: Professional installation is recommended to ensure safety and optimal performance.
Troubleshooting & FAQ
Why Choose JLM MARINE?
- Precision Fit: Cross-reference matched to Volvo Penta 3854905 knock-sensor applications on the listed 4.3L / 5.0L / 5.7L stern-drive packages.
- Quality Control: Each batch is inspected for dimensional consistency and workmanship.
- Direct from Manufacturer: Aftermarket marine parts engineered for reliable ignition-knock sensing service.
We can ship to virtually any address in the world with free shipping available for most regions.
For our typical US and Canadian customers , our shipping timeframes are as follows:
- Amazon FBA: orders will be delivered within 1-5 business days after placing the order (during certain special periods such as major promotions, Christmas, etc., the delivery time of Amazon FBA may be affected).
- US warehouse shipment: orders will be delivered within 5 days after placing the order.
- China warehouse shipment: orders will be delivered about 12 days after placing the order.
When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.
Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.
Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.
As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.
We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.
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