Code Details
| Display code | SPN 110 FMI 0 |
|---|---|
| SPN | 110 |
| FMI | 0 |
| OEM code | None listed |
| Manufacturer | Detroit Diesel |
| 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 DD15 cooling system must reject the significant heat load generated by a large-displacement engine under highway load. When coolant temperature exceeds the warning threshold, the thermal balance has been disturbed �?the cooling system cannot keep up. Prompt investigation of coolant level, fan engagement, and radiator condition is essential. On Freightliner Cascadia and Western Star trucks with the DD15, DiagnosticLink records the fault event snapshot for SPN 110 FMI 0 including peak coolant temperature, vehicle speed, and engine load at the time of the fault. This context is key for distinguishing a one-time thermal event during an unusually demanding grade climb from a chronic cooling system problem. A radiator that has been road-damaged from debris impact may show reduced cooling capacity only under maximum load conditions and pass a visual inspection at idle.
SPN 110 FMI 0 is Engine Coolant Temperature above normal on the J1939 bus. On the Detroit DD15 MCM2.0, coolant temperature is monitored at the engine outlet. The MCM manages the viscous fan clutch based on coolant and charge air cooler temperatures. A persistent FMI 0 reading �?not just a brief spike under extreme conditions �?indicates the cooling system is unable to maintain temperature balance. DiagnosticLink provides coolant temperature and fan engagement data for a complete diagnosis.
Common Symptoms
- High coolant temperature warning lamp
- Engine protection derate may activate concurrently
- Possible steam from the coolant overflow in severe cases
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Low coolant level from a leak or coolant loss
- Thermostat stuck closed
- Radiator face blocked by debris or insects
- Viscous fan clutch not engaging correctly
- Water pump worn or cavitating
- Coolant temperature sensor fault
First Checks
- Check coolant level in the overflow tank immediately
- Inspect the radiator and CAC (charge air cooler) face for blockage
- Connect DiagnosticLink and monitor coolant temperature, fan engagement duty cycle, and coolant flow rate if available
- Check for external coolant leaks from hoses, water pump, radiator, or EGR cooler
- Verify thermostat operation if temperature is slow to come up but then spikes high
- Review the fault event snapshot in DiagnosticLink — note vehicle load and speed context at the time of the fault
- Inspect the radiator core for debris impact damage that would reduce air flow in specific sections
Can I Keep Driving?
Reduce engine load immediately. Stop if temperature continues to rise. Operating above the protection threshold risks head gasket or engine damage. This is a critical fault requiring immediate attention.
Related Codes
Related Lookup Pages
Sources
- Detroit Diesel Service and Diagnostic Resources — Public Reference Detroit Diesel (Daimler Truck North America) · oem · accessed 2026-06-11 · confidence medium
Source: Detroit Diesel (Daimler Truck North America), Detroit Diesel Service and Diagnostic Resources — Public Reference. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - DiagnosticLink Detroit Diesel Corporation · oem · accessed 2026-05-05 · confidence medium
Source: Detroit Diesel Corporation, DiagnosticLink. 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
Why does the Detroit DD15 viscous fan clutch sometimes fail to engage when needed?
The DD15 uses a viscous fan clutch controlled by the MCM via a solenoid. If the solenoid fails, the clutch control circuit has a fault, or the clutch itself is worn, the fan may not engage at the correct temperature threshold. DiagnosticLink can read the commanded fan duty cycle and the actual fan speed sensor (if equipped) to confirm whether the clutch is responding to commands.
How common is EGR cooler failure causing coolant loss on the Detroit DD15?
EGR cooler failure �?leading to coolant loss into the exhaust and eventual overheating �?has been documented on various DD15 generations. Signs include white or steam-like exhaust, unexplained coolant consumption without external leaks, and rising coolant temperature. DiagnosticLink EGR system tests and a coolant pressure drop test with the engine off can help identify an EGR cooler leak.
Does the Freightliner Cascadia with a DD15 have a different cooling system than Western Star applications?
The DD15 engine cooling system hardware is the same across Freightliner Cascadia and Western Star 4900 applications. Differences exist in how the radiator and cooling airflow are packaged in the respective chassis, but the MCM-controlled fan clutch, thermostat, and coolant circuit architecture are the same.