Code Details
| Display code | SPN 110 FMI 0 |
|---|---|
| SPN | 110 |
| FMI | 0 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine �?cooling system |
| Component | Engine coolant temperature sensor / cooling system |
| Source address | Unknown or not applicable |
| Severity | stop safely |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The ISB 6.7 is used in everything from Dodge Ram 2500/3500 pickups to medium-duty delivery vans and box trucks. Regardless of application, overheating damages the same critical components: cylinder head, head gasket, pistons, and liner bores. When the warning threshold is crossed, immediate attention is required. On Ford F-650/F-750, International, and Kenworth Class 5-6 trucks with the Cummins ISB 6.7, the cooling system thermostat is a conventional wax-element unit. Insite monitors coolant temperature in real time and records the fault event snapshot. A thermostat that opens too early — allowing cold coolant into the radiator before the engine reaches operating temperature — can produce oscillating coolant temperature that never reaches the optimum range, which affects combustion efficiency and EGR operation. Insite can confirm this pattern by showing coolant temperature variation during a warmup drive cycle.
SPN 110 FMI 0 is Engine Coolant Temperature above normal. On Cummins ISB 6.7 CM2150/CM2350 engines, coolant temperature is monitored at the engine outlet and used for fan control, ignition timing adjustment, and engine protection. Cummins Insite can monitor live coolant temperature and cooling system parameters to identify whether a sensor, thermostat, coolant level, or mechanical fault is responsible.
Common Symptoms
- High coolant temperature warning lamp or gauge reading
- Engine protection derate may be active
- Coolant loss if a leak is causing the temperature rise
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Low coolant level from a leak
- Thermostat stuck closed
- Radiator partially blocked
- Fan clutch not engaging
- Water pump impeller damaged or slipping on the shaft
- Head gasket failure introducing combustion gases into the cooling circuit
First Checks
- Check coolant level in the overflow reservoir
- With the engine cool, remove the radiator cap and check for oil contamination or combustion bubbles that would indicate a head gasket issue
- Connect Cummins Insite and verify coolant temperature vs. expected values
- Inspect for external coolant leaks from hoses, water pump weep hole, or radiator
- Monitor coolant temperature warmup curve in Insite — confirm stable operating temperature is reached and maintained
- Check coolant concentration with a refractometer — low coolant concentration raises the freezing point but also reduces cooling capacity
Can I Keep Driving?
Stop or reduce load if coolant temperature continues to rise. Overheating the ISB 6.7 risks head gasket failure and cylinder head damage, which are expensive repairs.
Related Codes
Related Lookup Pages
Sources
- Cummins INSITE Service Tool — Public Reference Documentation Cummins Inc. · oem · accessed 2026-06-11 · confidence medium
Source: Cummins Inc., Cummins INSITE Service Tool — Public Reference Documentation. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - QuickServe Online Cummins Inc. · oem · accessed 2026-05-05 · confidence medium
Source: Cummins Inc., QuickServe Online. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium
Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
Are Dodge Ram 2500/3500 Cummins ISB 6.7 trucks more prone to overheating in certain applications?
Pickup trucks with the Cummins ISB 6.7 used for heavy towing or upfitting with large aftermarket equipment can experience cooling challenges if the radiator airflow is partially blocked or if the cooling system capacity was not designed for the added heat load. Medium-duty commercial applications with the same engine typically have more robust cooling systems sized for their intended loads.
Can a cracked cylinder head be identified without pulling the head on a Cummins ISB 6.7?
Some signs of cylinder head failure �?white exhaust smoke, coolant loss without external leaks, oil contamination in the coolant, or combustion gases detectable in the coolant at the radiator cap using a combustion gas test kit �?can be identified without disassembly. These tests are more reliable than just looking for white smoke, which can also occur from a cold start in humid weather.
How often does the thermostat need replacement on the Cummins ISB 6.7?
The thermostat on the ISB 6.7 does not have a fixed replacement interval in most service schedules. It is typically replaced when symptoms suggest it has failed �?either stuck open (engine takes too long to warm up) or stuck closed (engine overheats). Some fleets replace thermostats preventively at high mileage overhauls. The cost of a thermostat is low relative to the potential damage from a stuck-closed failure.