Coolant Temperature High Warning Active
The VOLVO-PENTA-110-15 (Volvo Penta) diesel fault code means: Coolant Temperature High Warning Active. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- DIY impeller and thermostat parts $40-$150. Professional diagnosis and repair $200-$800 depending on root cause. Heat exchanger descaling or replacement $500-$2,000 at a dealer.
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Common Symptoms
- Coolant temperature gauge climbs into the red or upper warning zone on the helm display
- Yellow or red alarm light illuminates on the instrument panel with a temperature symbol
- Audible alarm sounds at the helm station
- Engine power feels reduced or throttle response becomes sluggish as derate kicks in
- EVC display or multifunction display shows SPN 110 FMI 15 fault text
- Engine RPM may be capped below normal wide-open throttle limit
- Steam or coolant smell from the engine room in severe cases
Probable Causes (Ranked by Likelihood)
- Raw water impeller worn, damaged, or failed, cutting seawater flow through the heat exchanger Very Likely
- Raw water seacock partially closed or raw water strainer clogged with debris, grass, or jellyfish Very Likely
- Coolant level low in the expansion tank due to a slow leak or head gasket seep Likely
- Thermostat stuck closed or opening too late, restricting coolant circulation through the heat exchanger Likely
- Heat exchanger core fouled with scale or salt deposits, reducing heat transfer efficiency Possible
- Coolant temperature sensor drifting out of calibration and reading higher than actual temperature Possible
- Keel cooler blocked or partially fouled on keel-cooled installations Less Likely
Step-by-Step Diagnostic Procedure
Stop the engine immediately if the temperature is at or above the red line. Let it cool for at least 30 minutes before opening the raw water system or coolant cap.
Check the raw water seacock at the hull fitting. Confirm it is fully open. Then pull and inspect the raw water strainer basket. Clean out any debris and reinstall before restarting.
Inspect the raw water impeller. On most D3, D4, and D6 engines, the impeller pump is belt-driven or gear-driven at the front of the engine. Remove the pump cover and look for broken or deformed vanes. A worn impeller is the single most common cause of overheating on Volvo Penta marine diesels. Replace it if there is any doubt.
Check the coolant level in the expansion tank with the engine cold. The level should be between the MIN and MAX marks. If it is low, top up with a 50/50 mix of approved coolant and distilled water, then look for the source of the loss (hose connections, heat exchanger end caps, waterpump seal).
With the engine warmed up, feel both raw water hoses (inlet and outlet of the heat exchanger). The outlet hose should be warm but not excessively hot. If little or no flow is felt, the impeller, strainer, or a blocked raw water passage is the likely culprit.
If raw water flow seems normal, suspect the thermostat. Remove it and inspect. You can bench-test a thermostat by suspending it in a pot of water on a stove and watching for it to open at the rated temperature stamped on the body (typically 71-82 C on Volvo Penta diesels). Replace if it does not open at spec.
If none of the above resolve the fault and you have access to VODIA diagnostic tool via the EVC system bus, read the live coolant temperature sensor value and compare it to a handheld infrared thermometer reading at the thermostat housing. A mismatch greater than 10 C suggests a faulty sensor. Sensor replacement and live data logging require VODIA or a Volvo Penta dealer service visit.
Do not continue operating the engine with this fault active. Sustained high coolant temperature can warp cylinder heads, damage injector sleeves, and cause head gasket failure on D4, D6, and D8 engines.
Frequently Asked Questions
What does Volvo Penta code 110-15 mean?
It means the ECM has detected coolant temperature climbing above the normal operating range and into warning territory. SPN 110 is the standard J1939 identifier for engine coolant temperature, and FMI 15 means the value is above normal but has not yet hit the hard shutdown threshold. The engine will derate power to try to bring the temperature back down. If the temperature keeps climbing, the ECM will trigger a shutdown to protect the engine.
Can I keep running with code 110-15 active?
Only long enough to get safely off plane and reduce load. Head toward the dock or anchor up. Do not push the throttle trying to run through it. The engine is already reducing power to protect itself, and continued high-RPM operation with high coolant temperature can cause serious mechanical damage within minutes.
How much does it cost to fix code 110-15?
If the cause is a failed raw water impeller, you are looking at $40-$80 in parts if you do it yourself, or $200-$400 at a yard. If the heat exchanger needs descaling or replacement, costs climb to $500-$2,000. A faulty thermostat is a straightforward DIY fix under $50 in parts. A Volvo Penta dealer service visit for diagnosis typically runs $150-$300 before parts.
Will the engine shut down automatically if the temperature keeps rising?
Yes. The 110-15 warning is the first stage. If the coolant temperature continues to rise and crosses the hard limit programmed in the ECM, the system will escalate to a shutdown fault (similar to FMI 0 or FMI 16 level). The engine will derate first, then shut down to prevent catastrophic damage. Do not ignore the 110-15 warning expecting the engine to manage itself. Get the cooling system sorted before the next trip.