MerCruiser Low Oil Pressure Alarm Switch Assembly 805605A1
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Low Oil Pressure Alarm Switch Assembly ā Part 805605A1
| Part Number | 805605A1 / 87-805605A1 |
|---|---|
| Brand | Mercury Marine / MerCruiser / Quicksilver |
| Official Product Type | Switch Assembly ā Low Oil Pressure Alarm |
| System | Engine Warning / Alarm Circuit |
| Thread | 1/8ā27 Male Pipe Thread |
| Electrical Terminal | Single #10-32 stud |
| UPC / GTIN | 745061279834 |
This is a genuine OEM low oil pressure alarm switch used in the MerCruiser engine warning circuit. When oil pressure falls below the switch threshold, it triggers the audible warning horn. This is not the oil pressure gauge sender ā the gauge sender is a separate component that may be installed on the same engine at the same time. Confusing the two is the most common ordering mistake for this part number.
Supersedes / Replaced By
- Supersedes: 817169 / 87-817169, 817219 / 84-817219, F700602, F708940, 38559
- Current OEM number: 805605A1 / 87-805605A1
- Aftermarket cross-reference: Sierra OP22900
Compatible Applications
Fitment spans multiple engine families. Confirm by engine serial number ā displacement alone is not sufficient.
- 3.0L / 181 CID Inline-4 ā 3.0L, 3.0LX, 3.0L MPI, selected 3.0L MPI EC
- 4.3L / 262 CID V6 ā selected carbureted and EFI/MPI applications
- 5.0L / 305 CID V8 ā selected carbureted and EFI/MPI applications
- 5.7L / 350 CID V8 ā 350 MAG Alpha EFI, 350 MAG Bravo MPI, 350 MAG MPI MIE, 350 MAG MPI Horizon, 5.7L Competition Ski, other selected sterndrive and inboard
- 6.2L / 377 CID ā MX 6.2L MPI MIE, selected 377 / 6.2L applications
- 7.4L / 454 CID ā 420/425, 425 Gen V, 7.4L MIE MPI, selected 454 MPI/EFI applications
- 8.2L / 502 CID ā selected 502 MAG MPI/EFI, sterndrive and inboard applications
- High-Performance ā selected 500 EFI, 575 SCi, and additional Mercury Racing / high-output applications where the parts diagram specifies 805605A1
- Diesel ā selected Cummins MerCruiser Diesel (CMD) 1.7L applications
Serial Number Notice
Because 805605A1 spans many engine generations, serial number verification is required for confirmed fitment. If you are not certain, provide your MerCruiser engine serial number when ordering.
When This Part Needs Replacement
- The low oil pressure warning horn does not activate during a confirmed low-pressure condition
- The warning horn stays on despite verified normal mechanical oil pressure
- Electrical testing shows a failed pressure switch
- The terminal is corroded, loose, or damaged
- Oil leaks from the switch body or threaded connection
- An earlier superseded pressure switch is being replaced
Always verify actual engine oil pressure mechanically before replacing the switch.
Related Parts
- Mercury MerCruiser Audio Warning Alarm Kit ā 816492A6
- Quicksilver #10 Stainless Lock Washer 26996 (Pack of 15)
- 816492A14 ā Buzzer / alarm housing assembly (search by part number)
- 48952 ā Water temperature warning switch (search by part number)
- 45076 ā #10-32 brass terminal nut (search by part number)
Parts Desk Insights
Most common customer issue: Ordering the oil pressure gauge sender instead of this alarm switch. A MerCruiser engine typically has both devices ā the sender feeds the dashboard gauge (variable resistance), while 805605A1 is an on/off switch that triggers the audible warning horn. If your warning horn is malfunctioning but the gauge reads normal, this switch is the correct starting point ā not the sender.
Best use case: Ideal for customers troubleshooting a low oil pressure warning horn that won't activate or won't turn off, or for scheduled maintenance replacement on high-hour engines. Also the correct replacement when updating from any of the superseded switch numbers listed above.
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
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us ā 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 ā 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.