Sierra 18-99398 Johnson Evinrude Trigger Sensor, 2 Cylinder, Replaces 585072, 584716, 583387

The Sierra 18-99398 is a trigger sensor for Johnson/Evinrude 2 cylinder outboard engines, serving as a key component of the ignition system that signals the ignition module to fire the spark at the correct point in the engine cycle. Accurate triggering is essential for smooth idling, reliable starting, and consistent power delivery, and a worn or failing trigger sensor is a common cause of hard starting, misfiring, or intermittent ignition faults on these outboards. This unit is built as a direct equivalent to the original Johnson/Evinrude trigger assembly, matching the mounting and electrical function of the OEM part it replaces. It is constructed with a metal housing for durability in the marine engine environment and is sized to fit within the compact footprint of the original component. The sensor is intended as a straightforward replacement for boat owners and marine technicians servicing older Johnson/Evinrude 2 cylinder outboards covering the 4 to 60 HP range, restoring correct ignition timing without requiring modification of the surrounding wiring harness or ignition module. Because ignition timing components vary across engine years and cylinder counts, buyers should confirm their engine's cylinder configuration and horsepower rating against the fitment details below before ordering.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99398
• Product Type: Ignition Trigger Sensor
• Fits: Johnson/Evinrude 2 cylinder outboards, 1977-2005, 4 to 60 HP
• Material: Metal
• Dimensions: 1 inch D x 1 inch W x 1 inch H
• Weight: 0.1 pounds
• UPC: 808282394318

Fitment

• Johnson/Evinrude 2 cylinder outboards, 1977-2005, 4 to 60 HP

Replaces (OEM)

• 585072
• 584716
• 583387

Frequently Asked Questions

What does the Sierra 18-99398 trigger sensor do? The Sierra 18-99398 is an ignition trigger sensor that signals the ignition module on Johnson/Evinrude 2 cylinder outboards to fire the spark at the correct point in the engine cycle, which is essential for reliable starting and smooth running.

What engines does the Sierra 18-99398 fit? This trigger sensor fits Johnson/Evinrude 2 cylinder outboard engines in the 4 to 60 HP range, covering model years 1977-2005.

What OEM part numbers does the 18-99398 replace? It replaces Johnson/Evinrude OEM part numbers 585072, 584716, and 583387.

Is the 18-99398 designed for 2 cylinder engines specifically? Yes, the Sierra 18-99398 is built for Johnson/Evinrude 2 cylinder outboard applications; buyers should confirm their engine's cylinder count before ordering.

What is the trigger sensor made of? The Sierra 18-99398 trigger sensor has a metal housing, chosen for durability in the marine ignition system environment.

How big is the Sierra 18-99398? The unit measures 1 inch deep by 1 inch wide by 1 inch high, sized to fit within the original trigger sensor's mounting location.

How much does the 18-99398 trigger sensor weigh? It weighs 0.1 pounds.

Is the Sierra 18-99398 an OEM part or an aftermarket equivalent? It is a Sierra-branded aftermarket replacement engineered to match the fit and function of the original Johnson/Evinrude trigger sensor it replaces (585072, 584716, 583387), not a part sourced from Johnson/Evinrude.

Can I install the 18-99398 myself? The Sierra 18-99398 is designed as a direct replacement for the original Johnson/Evinrude trigger sensor, so it installs in the same location and connects to the existing ignition wiring without modification.

What is included when I order the 18-99398? You receive one Sierra 18-99398 trigger sensor unit.

How does the 18-99398 compare to the original Johnson/Evinrude trigger sensor? The 18-99398 is intended to function as a drop-in equivalent to OEM numbers 585072, 584716, and 583387, matching the mounting and electrical role of the original part.

Will the 18-99398 work on a 4 to 60 HP outboard from any model year? The Sierra 18-99398 is confirmed for Johnson/Evinrude 2 cylinder outboards spanning the 1977-2005 model years within the 4 to 60 HP range; engines outside that span or cylinder count should be checked against the listed OEM cross-reference numbers first.