Code Details
| Display code | SPN 110 FMI 0 |
|---|---|
| SPN | 110 |
| FMI | 0 |
| OEM code | None listed |
| Manufacturer | Cummins |
| System | Engine �?cooling |
| Component | Cooling system / thermostat / coolant temperature sensor / radiator |
| Source address | Unknown or not applicable |
| Severity | stop safely |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-12 |
Plain-English Meaning
The ISB 6.7 cooling system must remove heat from the engine block and EGR cooler. When coolant temperature rises above the normal range, SPN 110 FMI 0 sets and the engine protection system activates. The ISB 6.7 is used in medium-duty trucks (Freightliner M2, Kenworth T270, Peterbilt 325, International MV) as well as buses, and cooling system issues may be compounded by the HVAC loads present in bus applications. On Ford F-650/F-750, International, and Kenworth Class 5-6 trucks with the Cummins ISB67 (ISB 6.7), the cooling system fan is belt-driven with an electronically controlled viscous fan clutch. Insite can command the fan on and off during diagnostics to verify engagement. A fan clutch that engages at the correct temperature threshold but does not lock solidly enough to prevent slippage at maximum load is a difficult fault to detect at idle — a loaded road test with Insite monitoring coolant temperature and fan speed confirmation is the most reliable approach.
SPN 110 FMI 0 is Engine Coolant Temperature above normal range. On ISB 6.7 CM2350, Insite displays live coolant temperature, thermostat outlet temperature, and fan clutch state simultaneously. The fan clutch state data in Insite is a critical diagnostic reference for determining whether the fan is engaging when coolant temperature rises.
Common Symptoms
- Coolant temperature warning on the dashboard
- Engine protection derate or shutdown may occur at high temperature
- Steam or coolant loss if a leak or overpressure event occurs
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Low coolant level from a leak or inadequate maintenance
- Fan clutch not engaging at high temperature
- Restricted radiator from debris or scale buildup
- Stuck thermostat
- Coolant temperature sensor fault giving false high reading
First Checks
- Check coolant level and inspect for leaks
- Connect Insite and monitor live coolant temperature and fan clutch engagement status
- Inspect the radiator for external debris
- Verify the thermostat opens at the correct temperature
- If coolant level is correct and fan engages, suspect the coolant temperature sensor circuit
- Use Insite to command the fan clutch on and verify it locks at rated RPM without slippage
- Perform a loaded road test with Insite monitoring coolant temperature to reproduce the high-load thermal condition
Can I Keep Driving?
Reduce load and investigate immediately. Continued high temperature risks engine damage.
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
Is the fan clutch on the Cummins ISB 6.7 electric or thermostatic?
The ISB 6.7 fan clutch is electronically controlled by the engine ECM but may be thermostatic in some applications. Insite can display the commanded fan clutch state (on/off) versus actual state. If the ECM commands the fan on but coolant temperature continues to rise, the fan clutch is likely mechanically failing. If the ECM does not command the fan on, a calibration or sensor issue is suspect.
Does the ISB 6.7 in bus applications overheat more than in truck applications?
Bus applications add HVAC heat loads and stop-and-go duty cycles that can challenge the cooling system. In Cummins ISB 6.7 bus applications, the radiator sizing and fan clutch calibration may differ from truck applications. Confirm that the cooling system specifications match the actual bus application when investigating a chronic overheating complaint.
Can I add water to a Cummins ISB 6.7 in an emergency overheating situation?
In an emergency, plain water can be used to prevent an overheated engine from suffering catastrophic damage. However, water alone does not provide freeze protection or corrosion inhibition. After the emergency, drain and refill with the correct Cummins-approved coolant mixture (DCA-treated distilled water and ethylene glycol) as soon as possible. Adding water to a hot engine requires caution �?allow the engine to cool before opening the radiator cap.