YANMAR-LOW-COOLANT serious Yanmar ›

Yanmar Marine Low Coolant Alarm

The YANMAR-LOW-COOLANT (Yanmar) diesel fault code means: Yanmar Marine Low Coolant Alarm. This is a serious severity code.

Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.

My Garage →
Keep driving?
Limited driving only
DIY difficulty
beginner
Estimated cost
$25-$600

What Are the Symptoms of YANMAR-LOW-COOLANT?

  • Low coolant lamp / buzzer

What Causes YANMAR-LOW-COOLANT? (Most Likely First)

  • Leak at heat exchanger end cap O-ring Likely
  • Leaking coolant hose Likely
  • Cracked expansion tank on older YM series Possible

Can I Still Drive with YANMAR-LOW-COOLANT?

Limited driving only. YANMAR-LOW-COOLANT is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.

Frequently Asked Questions

What is Yanmar code MARINE-LOW-COOLANT?

Yanmar MARINE-LOW-COOLANT: Yanmar Marine Low Coolant Alarm. This code is reported on Yanmar equipment running the described engine family.

Can I keep working with Yanmar code MARINE-LOW-COOLANT?

Limited operation only -- finish the current task then shut down for repair.

How much does Yanmar MARINE-LOW-COOLANT cost to fix?

Estimated repair cost: $25-$600. Off-road diesel shop labor runs $125-$175/hr in 2026. Dealer diagnostic software (Yanmar SmartAssist / YDT) is usually required.

Mechanics Guide Step-by-step diagnosis

How Do You Diagnose YANMAR-LOW-COOLANT?

  1. Pressure-test cooling system to locate leak.

  2. Inspect heat exchanger end caps for seep stains.

  3. Top off with Yanmar-approved ethylene glycol.

Which Vehicles Commonly Get YANMAR-LOW-COOLANT?

  • Hunter / Beneteau / Catalina sailboats with Yanmar 3JH / 4JH
  • Trawlers and sport fishing boats with Yanmar 6LY / 6LF series
  • Sailboat auxiliaries with Yanmar 2YM / 3YM / 3JH5 diesels
  • Commercial fishing vessels with Yanmar 6LY3-UTP
  • Yachts with Yanmar 6LY400 / 6LY440 / 8LV common-rail marine diesels
  • Workboats with Yanmar 4LV / 4JH series marine propulsion
  • Ski boats and express cruisers with Yanmar marine diesels
  • Tenders and RIBs with Yanmar 3YM20 / 3YM30 sailboat aux
  • Island-hopper ferries with Yanmar 6AYM / 6HYM commercial series
  • Tug boats and small workboats with Yanmar 6HAL-HTP / 6HYM

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