Universal 1/8 inches NPT Temperature Sender for Oil/Water Monitoring (0–150°C / 0–300°F)

Universal 1/8" NPT Temperature Sender for Oil/Water Monitoring (0–150°C / 0–300°F) – Replaces Mercury 12415

This universal temperature sender is designed for Mercury and Mariner outboard and inboard engines that require OEM part number 12415. It accurately monitors oil or water temperature, providing reliable readings for engine management.

This unit serves as a direct replacement for Mercury part 12415 and Sierra part 18-5896, ensuring compatibility and straightforward installation.

• Thread Size: 1/8" NPT (18-27 NPT threads)
• Operating Range: 0–150°C / 0–300°F
• Installation Method: Direct Thread-In with Single Wire Connection

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 × Temperature Sender Unit (12415)

Installation Guide

1. Ensure the engine is completely cool and disconnect the boat's battery.
2. Locate the existing temperature sender on the engine block or cylinder head.
3. Carefully disconnect the single wire terminal from the old sender.
4. Place a rag underneath the sender to catch any minor fluid drips.
5. Using an appropriate wrench, unscrew and remove the old sender from the engine.
6. Clean the threads in the engine port to ensure a clean sealing surface.
7. Apply a suitable thread sealant to the threads of the new sender.
8. Install the new sender, first tightening it by hand and then securing it with a wrench. Do not overtighten.
9. Reconnect the wire terminal to the new sender.
10. Reconnect the battery, start the engine, and check for any leaks around the new sender.
11. Verify that the temperature gauge is providing a reading.

Troubleshooting & FAQ

Q: How do I confirm this sender fits my Mercury engine?

A: This sender replaces OEM part 12415 and uses a standard 1/8" NPT thread. The best way to confirm fitment is to check your engine's service manual or visually compare your existing sender's specifications with those listed here.

Q: What are common signs that my current temperature sender is failing?

A: Signs of a failing sender include the temperature gauge not working, providing erratic or inaccurate readings (e.g., staying at zero or jumping to maximum), or triggering false overheat alarms.

Q: Is this a direct replacement for the Sierra 18-5896 part?

A: Yes, this sender is a direct aftermarket replacement for both Mercury 12415 and Sierra 18-5896.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.